Volkswagen Forum - VW Forums for Volkwagen enthusiasts - APrils fool prank 07 GTI

Hey guys, new member here. Not really a VW enthusiast, but i'm sure you'll all love what i'm about to do...haha

Just a bit of BG info, I do know how to wire things up. I've done things like wire up a standalone ECU. I just don't know the schematic on the GTI.

I need some assistant from someone knowledgeable of GTI wiring. My buddy has a 2007 fully loaded GTI, DSG and all. For april's fool, i'm gonna steal his car for a few hours at night, and do a little bit of customization. I'm hoping someone can tell me which one is the easiest to do

I'm wiring his horn to something...few ideas so far, maybe you guys can chim in on more.

Things i don't want to do:
- i don't want to cut any wires, i hope to be able to just force the wire in to the back of the harness plug, and tape it in place. That way everything is reversible without damage.
- I don't want him to know this until he's on the road. Correct me if i'm wrong, but the automatic gearbox requires you to step on the brakes before you can move the lever...so the brakes might be out of the question?

Ideas so far:
- hook the brakes pedals (or brake lights) up to the horn
- night light to horn
- is it possible to take a connection from the fuse box in the engine bay, and hook it up to the horn? i.e. the night light's fuse, and hook that up to the horn?

is there anything that shares the same fuse as the horn? That way they'd be on the same circuit and fuse won't fry from crossing circuit.