It's hard to make this one flow well, but the whole point is "yabai" can mean both "dangerous/bad" or "cool/awesome". I guess "bad" is kind of close in English, although used that way it's a bit old-fashioned by now, I think... but I can't think of a better pun right now.
People named "Watanabe" don't need to throw beans around on Setsubun!Wow, really!? Watanabe's the strongest, ain't he!Watanabe's bad...Watanabe's bad, all right...Watanabe's real bad...What's going on?Watanabe's real strong, right!?... Watanabe's so bad!Watanabe's a badass, right!?Watanabe is bad.ヤバイ (yabai) literally means "dangerous", "risky" or "bad", but also as a slang word means "cool", "awesome".Seems a long time ago, Watanabe no Tsuna cut off the arm of an oni and ever since they've been afraid to go near the Watanabe clan!Watanabe's bad news...