[rosegal12]

She accidentally cut it with dog nail clippper, do I need to take him to a vet?

[smoothy]

she accidently cut it with dog nail clippper, do I need to take him to a vet?

How could she possibly do that accidentally?

Yes take the poor thing to a vet... and take those clippers away from her before she does worse.

[odinn7]

This can't be real... how would you accidentally do that?

There she was, just cutting the dogs nails when all of a sudden, his penis got in the way? Really?

If your penis was "accidentally" cut, would you want to see the doctor? Yes... take the dog to the vet and throw the nail clippers away.

[LadySam]

In almost 13 years I've never seen a penis cut accidentally by nail trimmers, I simply don't see how this could be done. Take him to the vet, the risk of infection is too high to take a chance, the cut would have introduced nasty bacteria into the wound (imagine what may be on a dogs nail)
Even if the cut does not look that large you don't want to risk that area getting infected.
Accidental or careless or difficult dog to trim, either way strongly consider having his nails professionally trimmed by a groomer of at your vets office from now on.