まさか
まさか · masaka · JLPT N3 · expression
by no means
Sounds like Ma's a car?! — by no means, surely not!
まさか is the gasp of disbelief: no way, surely not, by no means. The pun works the same way, because Ma's a car? is a claim you'd reject at once. On its own it's an exclamation (まさか!), and it can also start a sentence: まさか彼が… (surely he didn't…).