This is just horrible, let the poor bastard climax.

I've always found this funny. Stopping the cum from coming out doesn't remove the pleasure of the orgasm. Try it and see.

Shouldn't the band be just below the head in stead of further down the shaft?

No. The idea isn't merely to stop climax,* but to constrict the blood vessels, keeping the blood in the penis and therefore keeping it from softening.

This is dangerous and stupid, and should never be done.

• This wouldn't work anyway. Climax would occur whether you keep the semen from coming out or not.

there should be a tag for tying up a penis, it is actually a sort of bondage. this is a prime example of a potential tag: "penis_choke"