Partner 1 (First name later in alphabet): Secure a stop watch. Then ask your partner refrain from using any sources except their brain and to name as many mammals as they can in 60 seconds. Start the time. Keep a tally of all plausibly mammalian creatures named in this time period.
Prepare to submit a count of mammals named. Deduct animals that are obviously not mammals.
Switch and ask the person who was just tallying to name as many mammals as they can in 60 seconds.