Overkill

Blast a rabbit with a hand cannon - overkill indeed. The important bit: shooting a rabbit counts as killing an animal, which wrecks Lent. So do this on a throwaway save, or leave it until after you've secured the Lent trophy - never on your clean no-kill run. Otherwise it's trivial: find a rabbit, aim the gun (fire from the hip if aimed shots drift high on you) and pull the trigger.