How about this one...

PC looks up as a rather massive shadow falls over the party. Above them is a really, really massive red dragon (described as being about the size of a city, perhaps even Waterdeep).

Player: I drink my potion of red dragon control, and try to control Vlad (the Red; dragon).

DM: You sure?

Player: Yeah! It'll be cool to have that under my control!

DM: Okay... You drink the potion, and try to control Vlad... who shrugs it off, and now looks about to see the source of the strange sensation that rolled over him.

Player: Hmmm... What to do?

DM: He notices you, and swoops down to take a closer look.

Other Players (collectively): You idiot!

Player: Oh well... Time for a barbeque... (Last words before massive flame incinerates the party)
"Expect to be tested, and rise to the challenge, no matter what difficulty and pain it brings."