Wolverine undoubtedly fights well above his paygrade on a very regular basis. Despite his undoubtedly great fighting ability, impressive regenerative abilities and adamantium-laced skeleton and claws, he's still merely a peak human and he often gets a little bit over-confident, even when faced with characters out of his league. Consequently, he sometimes needs knocking down a peg or two and that's exactly what Ben Grimm did in 1987's Fantastic four Vs the X-Men. When Wolverine was getting a little cocky, Grimm gave him a little tap on the head (accompanied by a wonderful "BONK" sound effect) and rendered him unconscious. He then said "sweet dreams, Bub", mocking the mutant's trademark word.
