4th year

A student in their masters year (perhaps of a mathematics degree) who, due to their familiarity/over experience of the workings of the campus and local area, has devloped a level of smoothness and desceptive confidence that most women find irresistable. Gentlemen who are truly skilled in the ways of the '4th' may opt to use the deadly 'kid that got picked last in P.E.' technique whereby women percieve them as such a low threat due to their unworldly aura and gaunt physique that they take pitty, letting down their defences and making them an easy target. It is unclear whether or not there is a woman that a '4th year' would turn down, but their is one thing for sure and that is that if he does go home with a girl, he'll make sure no one else has any chance of finding out.

When medical students have non-stop happy hours during their last year of medical school since they actually have time to do things. It's part of the their ritual attempting to have real lives before residency starts.