While engaging in sexual intercourse at the climaxing moment the man displays his masculinity and prowess by alerting all of his fellow housemates (possibly roommates) that he has finally scored. He does this by mimicking at full volume the 'horn of gondor' from lord of the rings. This works especially well in a uni dorm with thin walls.
'At the climaxing moment... oh yeah, oh yeah, oh ye... AAAAAAAARRRROOOOOOOOOOOAAAAHHHH... AAAAAAAARRRR...SLAP'
'Did you hear me Horn of Gondor the entire womens rugby team last night?'