I was snooping around and saw a user with Seedbonus: -34.
Is that a punishment of some kind? Can you get below zero? The question is not too urgent so I ask it in chitchat.
Yes it can. I won't call it as a punishment but as a "result", a bad one. Maybe the user was too exited posting topics or comments, just too much and inappropriate, got reported and his topics or comments deleted. The bonus took away from him. If the user already spent the seed bonus, the result could be the one you saw.
And, not only seed bonus can be on below zero, Reputation Power could be also below zero. You can see them on this Forum Stats