My 3yr old son stands up to wee but when I sit him on for a poop he will have a wee at the same time. When I lift him off I have noticed his pants are sometimes wet at the back. They were dry before I sat him on and his penis was pointing into the toilet.
Why are his pants wet? He gets very upset because of this.
He is not fooling about because I am with him all the time.

It's probably going out between the bottom of the seat and the top of the bowl. There's a small gap there.

I remember having wet pants or seeing a puddle on the floor after sitting on the loo for a poop. My mother used to smack me and say I was a naughty boy for having a wee at the same time as a poop. She said I should stand for a wee and sit for a poop.

Thank you for your replies.
His wee was going out between the bottom of the seat and the top of the bowl.