When male twins take part in a sexual activity together.It has to be only with the two hence "Double".The "T" doesn't mean twin, but taboo.Also know as T&T-ing.The term has been used toward Brother-Sister twins relationship,But is wrong.It could also be used for males with a Bromance who treat each other as brothers.
I went into their room and Jacob and Jack were Double T-ing.
by Cosplayteam37 March 10, 2010
Get the Double T-ing mug.