The old Crossfire CB trick/bug

Today i was playing CF, i ran into this guys and he was doing a trick in Lab B site, i heard his breath up on vent, but actually he wasnt there, he was somewhere else. I asked him if it was a trick or something and he said yes, its an Old Crossfire, Close Beta trick. Anyone knows about this?

This is just the game with it's usual error's believe me its happened to me a few times