Boston skid mark
A male sexual manoeuvre that involves defacating before the encounter and skipping the wipe, then proceeding to mount one's partner in "la cubana" fashion (more commonly known as "titty fucking"). The after-effects of such a manouevre tend to leave your mark, in this case the Boston skid mark.
Oh bra everything was going so nice until she started pushing for a Boston skid mark. I had to bail.