I will! It stops being a joke and starts being mean if someone gets hurt!

[Diarmuid nods at Silver and then looks toward where Horsea is bobbing in the water.]

You heard that, right? You can't spray too hard. We don't want anyone getting hurt!

[Horsea makes a soft squeaking sound and then shoots a small stream of water. It isn't very strong and lands just a short distance away from the pokemon without hitting anything. This causes Diarmuid to giggles and look back at Silver.]

I think that is his way of saying 'yes!'