The act of always talking about girls (usually young) but never acting on the words due to lack of charm/shyness/hyper-controlling girlfriend
Derek - "Woah guys, check out that hot piece of ass doing her A-levels. I'd plough that like a freshly grown field"
Guys - "Shut up Derek, every time your girlfriend goes away you go all brunstrom on our asses. Cut it out and get back to tickling your bald eagle"