Pussy tailing is when a Guy likes a Girl and follows her around trying to get into her pants. The guy will attempt to do this by complementing her, admiring her, sticking up for her and generally flirting wit her.
Also related to cock chasing which is when a girl follows a guy around because she likes him. Same as pussy tailing but roles reversed
Guy 1: *hanging wit agroup of girls* Hahahahahahaha *laughing at a poor joke* thats so good
Guy 2: *away from group talking to his real mates* Look at Dave, hes pussy tailing again. Twat.
Girl 1: hahahahahahahahahahaha