To chinrest, or the act of chinresting, is to be whipped by, and spend an excessive quantity of time with, one's girl friend; Often to the detriment of one's male friends. This word derives from the act of resting ones chin in the area between a girl's legs in order to to perform cunningilus for up to hours on end.
"Where's Mike? Oh he's off at his bloody girl friend's place again giving his chin a good rest
"Kara's never at the flat these days, now that he's away chinresting all the time at Holly's!"