Get into the showers while no one's there, naked if thats fine with you. Piss yourself. Don‘t just let it go, but try to piss all over yourself. Only when your sure that people are coming, you‘re allowed to start the shower.

My showers will be at the pool and most there will most likely be a friend with me

Strip naked and leave your towel in the cubical, you must walk to the showers naked and back

Wear panties and your girliest socks while changing and keep your panties on in the shower.

My showers will be at a pool and there most likely will be a friend with me

When getting dressed again after your shower give yourself a wedgie in full view of the rest of the locker room.

Strip completely naked before you have even chosen your locker. Make sure your in full view of everyone when drying after the shower too.
My showers are private. The locker room has a central seating area in full view of everyone. No toys. Willing to do pretty much anything in the locker area except cum/piss