I would have been able to say two at one time, ironically the 2nd one being Irish, but there's just no reason to use it now so I'd be rusty as hell with it now. Still though, it really has its uses like talking shit about people you don't like (in other countries of course) to their face or around them within earshot. Chances are nobody will understand you, but then again you do have to be careful depending on where you go to.
I had reasonable French at one point too, but that's long forgotten now.
The only thing I can say however is that I do have the ability to tell you to "Go Fuck Yourself" in several different languages.