What in the Flub...?

 

Regular readers (both of them) will be aware that I often become obsessed with details in the background...and today is no different.

There's a band or musical group in the background, and the squeeze-box is easy to spot.

But what are the other two guys playing? It looks like some sort of snorkel-kazzoo, or maybe some sort of jew's harp?

Can anyone help?

Bonus -