I've always been a prankster. As hard as I tried not to let it fade into my work life, it has. Horribly. There are a lot of pranks I'd be willing to share over a beer, but these are the one's I can share online off the top of my head.
Twice while overflying SFO, I've called my airlines ops and said something like: "6969 is 10 out, we need a lav, bug wash, 19 wheelchairs, and 11 of them are aisle chairs. We also need maintenance for a shoe that clogged the lav". Now the first time I did it, my company was still doing our operations and a friend was working. He replied "Wait what?! 6969...are you a ferry flight? Where are you coming from I don't have you on igaps or radar". Then I just keyed the mic laughing and he laughed back, and just figured it was one of his pilot coworkers or maybe even one of our pilots kidding around. I later told him it was me, he said he liked it. After United took over our operations, I tried it again since I monitored and heard the voice of an ex-coworker who moved to United. She seriously flipped her lid that someone was messing around on frequency(when it was totally dead) and I'm pretty sure she later came the the conclusion it was me, seeing as she does hear my voice on the radio all day at work and knows I'm a pilot. Since then she's constantly trying to pin delays on me, and everyone keeps asking what I did to piss her off.
I was assigned some new-hires recently at my gate for OJT, and the first time I had either of them in the pit of a CRJ, I started screaming at them to remove the box that is bolted to the floor. They would just tug and tug and I'd keep shouting stuff like, "C'mon its a quick turn! I've seen 110 pound girls lift boxes bigger than that out here!". Finally, I come up the belt loader and go, "Look, there's your problem, its bolted to the floor". One of them got it and laughed. The other asked how we get the bolts out.
I've told new hires "The push back is dead, both of you take a wing we're gonna push this Brasilia by hand". To my surprise, they always get ready to push.
When I'm wing-walking and see people staring at me out the window in a way that looks less than friendly(usually this is a person who was rude when I took their carry-on), I start grabbing my radio pretending to scream into it pointing at the engine of the airplane, then I shrug and walk back to the nose to disconnect. Either this or as the plane taxis away I get my crew to point at it and make shocked faces.
Sometimes I take unload the last bag and put it back on the belt loader, and everytime another agent reloads it, I put it right back. By the 2nd or 3rd time, they usually start to scratch their head. Especially if it isn't a black bag.
I told some new-hires they needed to change into full rain-gear to dump a lav, and they listened.
I once told a new-hire that with the -700s, you are supposed to salute until the CA salutes you back when you marshal out the airplane after the push. Watching this poor kid stand there at attention saluting the crew for a good 20 seconds while they just look at each other waiting for the kid to move and back at me like "wtf" as I just shrug my shoulders like I have no idea either...good times.
When F/O's ask me for a lav during their walk arounds(when one wasn't called in to ops), I usually say "No, no hablo ingles senior". 1/3 of the time, they just kind of stare at me, shrug, and walk away and I actually get away with it.
At my old flight school, one time I walked in after my last solo before taking my PPL checkride and asked the owner "How did the tail get ripped off of 591?", in a very serious and curious tone. He went "WHAT?!" and almost jumped over the 4 foot counter. I told him I was kidding, and he was furious. He called both my dad and CFI and told them I had maturity issues. I guess since he looked like Obama, I just figured he'd be cooler than that.
Sometimes when we're all ready to go but we have several minutes of airplanes blocking the gate and I know the plane isn't going anywhere for a while, I put on my sunglasses and sit on the edge of the push-back, putting me near eye-level with the crew. Although I'm looking all around relaxed, it appears as though I'm intently staring at them waiting for the push signal. Its funny how quiet the cockpit is when I do that, and how many times they ask if they're clear yet.
I told some new-hires once that when flight attendants ask them for crew-meals, it's code for them hitting on them and wanting their phone number. I know of at least one ramper writing down his phone number on a cargo load report, handing it to the FA, and joyfully walking away as she no doubt stood there confused still waiting for her crew meal.
I used to send out sarcastic raves(our companies version of a "good job" letter everyone can read online) about lazy employees and how they saved the day with their hard work in elaborate detail. Sometimes I would just say things like "So as I struggled with scanning and loading 60 bags in the rain, so and so used his smart phone to keep us all up to date on current events, for which I am eternally grateful." I think a few of them complained and I was asked to stop. But most people at the station thought it was great.
That's all I have for now. Good topic though.