partner Idiom, Proverb
partners in crime
people who plan and commit crimes together, boozing buddies As kids, Andy and I took apples from a neighbor's tree. We were partners in crime, so to speak.
sparring partner
sparring partner An individual with whom one enjoys arguing, as in
Jim's my best sparring partner. This expression alludes to boxing, where since about 1900 it has denoted the person one practices or trains with. [Mid-1900s] Also see
spar with.