Our sixth form boys have a thing with hanging out with girls 2-3 years younger than them, so the yr13s go with the yr10/11 girls, and the yr12s with the yr9/10s, we never got it (but were quite happy when it was our turn to be fancied by all the yr13s) We currently have one 20 year old dude whos going out with a 15 year old, it's just sick