Pilly foo is an intense case of bedhead
that one acquires in one of several ways. The most popular method of attaining pilly foo is to sleep for an extended period of time with already-messy hair at the time of going to bed.
Other methods include naps, getting attacked by a blowdryer, or letting your hair dry after swimming.
Man, did you see Mark's crazy hair this morning? He had some crazy pilly foo goin' on!