You'd either get mugged or gangbanged.
GANGBANGED
A virus can be caught from anyone.
There is nowhere you can these days. CCTV will catch you out even if you think nobody is watching as most Schools have it for security reasons.
there is not anyway to do this without getting caught
While - sad to say - a large percent of "friends of girlfriends" will cheat with you, they will never keep quiet about it. And the first person they tell, almost before you are done getting dressed, will be the girlfriend.
Spy on him! A wife caught a guy redhanded giving nude photos of himself to his girlfriend.
dump him/her because how can u still trust him/her
There is always a chance of getting caught, try covering your backdoor with many wingates.
the lead singer got caught cheating on his girlfriend
geotaughtaphobia
JAIL!