Taking toddlers for haircuts

We must have some mothers and fathers who have done this?

I don't have any children myself, but I tried to take my nephew for a haircut today and it was impossible.

It's his 2nd birthday on Sunday and his mother (my sister) wanted him to have his haircut before the day. She took him in the morning to the barbers and he was not having any of it. She then asked me if I'd take him in the afternoon, so I did, and it was much the same.

The barber said that it's generally okay if the kid is just crying, but if they're thrashing about with their arms and shaking their head it's impossible to do it. Completely understandable.

This would have been his second haircut. His first went by with ease. He sat there and didn't bat an eyelid.

Any suggestions on how to calm a toddler down for a haircut?