Is this a call?

I was in a tournament the other day, sort of a home tournament in that it wasn't set up by professionals, or a card room, etc.

Two guys are in the pot, one guy goes all in. The other says "I'm gonna double you up."

Then the guy who went all in flips his cards over thinking the other called. But the other guy argues that he didn't call and throws his hand into the muck.

What's the ruling here?