You must click the screen 50 times as fast as possible. This forces Eggman to snap the leg, allowing you to advance before the bomb detonates. The Community-Made "Impossible Sonic Lore" Quizzes Question 46 (The Impossible Quiz)
Because the original was a Flash game, you won’t find it on Newgrounds anymore. But the fan community has preserved it: impossible quiz sonic
Because Question 18 is a "trap" designed to end the run of players who click reflexively, here is the recommended strategy: You must click the screen 50 times as fast as possible
This is arguably the most well-known Sonic reference in the game. impossible quiz sonic