A LOT

I'm sure he's the original, since when he came back, his avatar popped back in on my friends

I like to pop, like I say the popper the merrier

Karl Popper was never particularly merry.

That Peter Popoff guy wasn't much fun, either.

There's always John Popper, but I think he may have been jollier than he was merry.

Poppin' Fresh

The Fish Popper

And then there is that Popper with the penguins, and Mr. Popper, a shampoo