A male slut.
An easy insult to use - 'your such a ramsden', 'he's got that ramsden way of life' and so on.
person1: Did you see Steve last night?!
person2: yeah.. typical fuckin' ramsden.
person1: yeah - how many was it? 3? 4?
person2: no! he beat his record of 7!
person1: ohhh yeah! the twelve year old!