Ew I have a friend (his name anonymous) who has a toe with green puss? WTF? ?

Ok eww but I have a friend and his toe will like swell up sometimes on the sides of his nail under the skin and he told me when he uses something sharp to pop it green puss comes out WTF? Don't even ask why he told me VERRY long story but yeah what's up with that?why does that happen to him? O_o *gets chills*