a bit on the side

a bit on the side

A person who is involved in a sexual relationship with someone who is married. Primarily heard in UK, Australia. I spotted Harry at the diner with a woman much younger than his wife. She must be his bit on the side.
See also: bit, side

a bit on the side

  (British & Australian)
if someone has a bit on the side, they are involved in a sexual relationship with someone who is not their usual partner He had a bit on the side for years until his wife found out. I knew she'd never leave her husband for me. I was just her bit on the side.
See also: bit, side