When I was at the Aptos, CA session last week someone started a polka. The name of the tune was "somebody Ryan's"; I think it might have been Peg Ryan's. I half-jokingly asked if "she" was related to John Ryan, at which point folks decided to play that tune as well.
I've just learned the tune and wanted to play along, but the session was playing it about three times faster than I could manage. People tend to do that with John Ryan's; it's one of the tunes which is simple enough that it actually sounds really good when played dizzingly fast.
But rather than sit out the tune altogether I just tooted along on the eighth note pairs that start every other bar (like the first pair of high Ds) and omitted the rest. This was all I could keep up with, but it actually sounded good with just those notes.
I heard another whistler at my regular session do a similar thing with Harvest Home. He's a pretty good whistler, so I suspect he was doing it just for the sound rather than because he couldn't keep up. At any rate, he didn't play any of the low As in the first three full measures in the second part. I also liked the sound of that, as a variation.