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.
by Nigel Fish May 18, 2006
Get the Regretgasm mug.