Lol
according to urban dictionary
To be omnipresent, omnipotent and revered, a true magician and miracle performer perfect in every way, often used by Gods and adepts to indicate a show off. In more mortal circles indicates a true divine purity that could never be attained, Gavin is the light so sought within each of the worlds religions. Ultimatley it is the purpose of all Gods and mortal beings to become Gavin.
Or
Gaven
an extremely large penis. Its a word that is becoming more common
Girl: have you seen the gavin on that guy!
Other Girl: no
Girl: OMG! its HUGE!