Determine the value of the number ABCD

Mick's wife was furiously humping away with her husband's best mate, Peter, when suddenly the phone rang. She hopped out of bed and returned to the sweaty sheet after a brief conversation.
"Who was it?" the back stabbing buddy asked.
"Oh, that was Mick," she replied calmly.
"Oh crap, I'd better be going then!" he said. "Did Mick say where he was?"
"Relax -- he's down at the pub playing a few games of pool with you."