1) Play Dalaran Diving (can be done with any other smallish body of water). Find a small body of water somewhere, stand 10 meters away, get on your flying mount and fly up as high as the game will let you. Then try position yourself over the water and dismount . See if you can land in it or not.
2) Collect a full set of gear that looks like caster gear when you are a tank (for example warriors can wear tier 0 Devout or Dreadmist gear).
3) Find a beggar that is spamming for gold, then go up to him and say “Hey <beggar name> hold on, stop spamming I want to ask you a serious question.” Then he will probably go “?????????????”. Now comes the crowd pleaser: “So in a fantasy world where you can choose to be a Mighty Warlord, a Powerful Magi, a Stealthy Assassin or a Defender of Light, you choose to role-play a homeless beggar. Why?” Watch everyone around you start laughing and applauding you.
4) Create a low level character and start sending funny and harmless insults at your friends but log off before they can respond.
5) Go stand in the middle of a high populated area like Stormwind and start having a conversation with yourself. Or try start a conversation with someone else who is in that area.
6) Try have a conversation with an NPC (it’s great if you can find one that has a lot of dialogue).
7) Play the Sweat and Sour game (yeah kids love playing this one from the back of their car window) /wave at someone and see if they wave back. If they wave they are sweet, if they don’t they are sour. If you have a lot of gold you could give the sweet people some gold.
8) Get on a lowish level alt, find a level 85 running around and try convince them to start a Bastion of Twilight PuG with you (even though you are low level). Just keep convincing them you are a really good tank / healer / dps and know how to play your class!
9) Talk in guild chat as if you are a Pirate (there are addons that turn your normal speech into pirate speech too). See how long it takes for them to get sick and tired of you doing it, or see how many you can get to join in.
10) Type a long, embarrassing whisper (think cyber sex) to a random person that you don’t know and say “Uh did I just send that to you instead of <Insert another random player that you don’t knows name>” - Even better if that second random person is friends / in the same guild as the first random person.
Can also be done with ingame chat channels, like send the misstell in Stormwind General chat etc.
11) Go to a questing zone and find a random person, then spend the next 10-15 minutes following them everywhere they go, see if they get annoyed with you. If they ask why you are doing that tell them they smell nice.
12) Beg until you get a total of 10 gold, then when the next person eventually gives you gold, give them the 10gold instead and say “You need it more than me, trust me!”.
13) Try create a group for a low level dungeon and only accept level 85s. If the group eventually fills up for some reason, then tell them in a sad tone that you don’t think the group will be good enough to clear the place and disband the group.
14) Find a beggar begging for gold, tell him he needs to get on your 2 man mount and you will take him to a secret gold making spot where he can get 1000g in 20 seconds. Then fly up really high and kick him off.
15) Get on vent with your guildies, then get a real life friend to roleplay your mother or father. Tell your guildies “brb” and pretend you forgot to switch the mic off. Then continue to pretend to have an embarrassing conversation with your mother/father.
16) Find someone with a really cool looking sword and offer them 5000gold for it. When they say “Sorry it’s soulbound dude.” Increase your price and ask them again…and again…and again.
17) Join a PuG for Bastion of Twilight or similar, then while waiting for the group to fill still, start advertising in trade that you are lfm for a Black Temple run or something. See if your raid leader answers. If you have invite powers, invite them to your raid before the raid leader notices!
18) Join a group and "accidently ninja" an item off a boss. When the group goes “WTF dude?!? Those are tanking leggings and you are a dps”. Tell them oh…I’m sorry I thought they were dps leggings, here you can have them. Give it back to them and then continue to exclaim how terrible you feel for doing that and tell them you are going to ticket a GM and turn yourself in for the “crime” you committed. See how the rest of your group reacts.
19) Try convince people around you (for example in Stormwind) to log off because they are causing you to lag, or because you and your GF want some privacy.
20) Fake achievements into guild chat such as type “has achieved [Link a very very hard achievement from your achievement log that you have not completed”. See how long it takes for people to notice that the achievement is still in progress. (Link something that people won’t need to click on to find out what it is). – Quite funny when you are level 85 and pretend of have only just attained level 85 now.
21) Announce in trade chat that you just finally reached level 80 and are so excited that you can finally start raiding and joining the rest of the high levels. Then when someone tells you that there has been an expansion and the max level is 85, rage and have a mental breakdown in trade chat, ending with you talking about how you got dumped in 6th grade.
22) Whisper a random person ingame and ask if you can marry them. Tell them you are lonely and dying or cancer and you don’t have long to live. Your last dying wish is to be able to say that you have been happily married.
23) Play cheat death game. Go to a deep body of water like the sea (in game please not real life) and go far far down. Then try time it so that by the time you reach the air above you are already starting to lose life from drowning.
24) Go to a popular Flight Point and start greeting or sending your farewells to anyone coming and going.
25) Get a bunch of friends together and have them all get Noggen Fogger Elixirs. Then all fly up really high to a certain place (for example the floating islands in Nagrand) and have them all jump off. You then have to spam your Noggen Fogger Elixir until you get the slowfall debuff. Don’t allow them to use slowfall, bubble, blink, iceblock, etc to negate fall damage or reduce fall speed.