Regretigans 

When shenanigans just aren't enough and you completely have gone beyond the definition of shenanigans and absolutely regret what you have done.

"OMG last night was SO crazy. I got into major shenanigans! I completely regret everything I did. I made out with (insert regretted name here) and came home soaking wet!"
"Dude...those aren't shenanigans...Those are regretigans!"

Regretigans by Raewow's Biggest Fan October 21, 2011

Regretgasm 

An orgasm that is immediately, or soon thereafter, regretted upon, as you were having sex with someone you should not have been having sex with.

I bumped into my bitch of an ex-girlfriend, and it ended with a solid regretgasm. I even yelled "NOOOOO" as I came, realizing my mistake.

Regretgasm by Nigel Fish May 18, 2006