(scene opens around cluttered breakfast table)
Me: (reading Kindle) So. Beta. Did you brush your teeth this morning?
Beta: (shoveling cereal into his mouth) Yeah.
Me: (conversationally) With what?
Beta: (spidey senses tingling) …with…toothpaste?
Me: Oh yeah? Where’s your toothbrush?
Me: (affected mildness) Interesting. Because I’ve noticed that your toothbrush has been bone dry for a few days, so I brought it down stairs with me at 6 am this morning so I could prove to you that I know you for a liar. So. When you’re finished with breakfast, go do that. The reason you’re getting cavities is not because you’re not brushing well enough, you’re not brushing at all.
Beta: (mopey, drinks last of milk goes to brush teeth)
Me: (calls after him) Also! Your toothbrush is electric and makes noise! I can tell you didn’t brush your teeth if I didn’t hear it! Sound travels! SCIENCE!