A priest, a minister, and a rabbit walk into a blood bank.
The rabbit says, "I think I'm a type-O."
Rabbit's Blood Type
Explanation
Explain Bear
Listen up, buttercup. This joke is based on wordplay, which I know is advanced for you. The rabbit says he is a "type-O", which sounds like a blood type. But normal folks know he is saying "typo," like a mistake. The rabbit is the mistake!