They hold a piece of magic rope across in front of them.
You begin to speak, but point out that you have a lump in your throat.
So you cough on the rope – and a knot appears out of nowhere in the middle of the rope!

You grasp the knot and untie it with the help of your other hand.
The rope is presented again without any knots – but if you wish, the account can appear again in a flash!
Strictly speaking, he can do this again and again, even as a running gag.