Utterly knackered...AKA breathing out of your arse...refers to the fact that you're hanging on by the chinstrap of your helmet.
I ran 10k's last night, I was utterly chinstrapped afterwards.
by HeeBeeGB July 24, 2006
British army slang to mean extremely tired or worn out. As if to be hanging from the chinstrap of ones helmet.
he was chin strapped after the 1o mile run
by rojoags June 02, 2009
During the performance of oral sex on a female, a bearded male will place his chin between the vaginal lips and shakes his head back and forth rapidly and lightly to induce a pleasurable experience for the female.
Shirley loves it when she gets Chinstrapped by John.
by Joey from AU November 21, 2007