That's cheating

Does this "homu" still count as an uncommon sound effect?

I don't think so. It's basically a character trait at this point.

TIME HAX!!! It's cheating!!!

That's way fast, but oh well, it's rather funny.

It was only 3 Taiyaki... o.o;

The "dooooon" is probably a jojo reference.
It's the sound effect used for when Dio "teleports" or appears suddenly because he stopped time.