That's the Kikōhō, right?Broly-san, you're awesome!SERIOUSLY, WHY?Bird!!
tl;dr it's that water dragon technique from really early into the showOx-Monkey-Hare-Rat-Boar-Bird-Ox-Horse-Bird-Rat-Tiger-Dog-Tiger-Snake-Ox-Ram-Snake-Boar-Ram-Rat-Jin-Monkey-Bird-Dragon-Bird-Ox-Horse-Ram-Tiger-Snake-Rat-Monkey-Hare-Boar-Dragon-Ram-Rat-Ox-Monkey-Bird-Jin-Rat-BoarHey, Broly-san! Do that thing!Ah! Goten, Naruto's on!You can do it!Come on, if you can do that then it should be a piece of cake!?WHY?HA!That I can do.not really, no...Circle with your fingers?See, you just have to make a circle with your fingers!