Jaguarandi in Cyber Troopers Virtual On. If you take too long to beat all FIVE of the first wave of Virtuaroids--"too long" varying from like 3:30 for all of them, or on harder difficulty, seemingly 3:00 even--the game decides that you're playing like a little bitch and sends you to the "penalty stage." Cue a boss that literally takes up one half of the arena, moves three times faster than you, has Raiden's moveset but on steroids and faster, and can kill every character in 1-2 hits. Also he takes about ten times the hits that a regular Raiden does, who's already the most defensive character in the damn game.
The funnier part is that the actual final boss is a total pushover that you basically only have to strafe to the right and fire to kill. And, again, players good enough to actually BEAT Jaguarandi (it can be done, thank god, but it's the most nerve wracking experience ever, especially if you're a lower-armored VR like Fei-Yen) WON'T EVEN ENCOUNTER HIM because they clear through the early levels so quickly. So players that are good enough will just blow by without ever seeing the fucker and players who aren't very good will FINALLY get far enough to go to the Moon half of the game and then HAHA NOPE YOU SUCK! BASICALLY INVINCIBLE SECRET BOSS JUST TO REMIND YOU YOU SUCK. And let's say that you're dodging him like a boss and whittling his health down. Too bad, you have 90 seconds, so you basically have to hit him with every hit you have while dodging his light speed screen-wide laser spam or you just automatically explode for taking too long to beat a nigh-invincible demon beast. Sucks to be a pussy, the game says!
Even better, if you continue and keep pumping quarters in, you can't actually bypass Jaguarandi. He'll keep showing up before you can go past him, shrinking slightly each time you fuck up, so you can basically keep paying to weaken him until he's literally the size of a single missile and just skitters around like a bug and dies in like three hits.
Then you remember this game cost 8000 USD for operators at the time, most places charged 1 or 2 bucks a pop to make up for this, and there's a damn boss to PENALIZE YOU FOR NOT LEARNING THE GAME FAST ENOUGH that requires you to keep pumping dollars in until you've paid for him to shrink enough for your bitch ass to beat him. Is it any wonder this game did so bad here?

It's fun and sadistic as hell though and a great game for a home arcade since there's shit like this that takes forever to beat and the multiplayer gets so deep as you and your friends get better.