As a friend of Doomguy you are allowed to be in range of his rabbit, Daisy. Daisy, with her ears cocked in her characteristic "I am interested in something" pose, appears curious about the new friend and does a hop toward you.

She sniffs the air in front of her, trying to figure you out, then gives your finger a friendly and playful nip. The nip is surprisingly gentle, and doesn't even break the skin.