We all know shaking hands or a handshake. There, we 'shake hands'.

There's one more gesture I do. I gently punch other's fist.

Something like this -

What do we call this gesture as a noun?

They close the deal with a handshake

The close the deal with (a?) ____________

Also, as a verb?

Whenever we meet, we shake hands

Whenever we meet, we ___________

If there's no single word, a couple would do.