That's one way to learn not to do something . . . .

"It hurt, but it was worth it"

Did he guess before he checked?

loplopsama said:

That's one way to learn not to do something . . . .

Still, you would think that wouldn't be the first idea to pop into his head.

Blue.Poison said:

"It hurt, but it was worth it"

Guess he'll just be in the dog house for a while.

Looking at his confusion, he's still half-asleep.

Guess he knew who was wearing what from the previous comic.

That's, a hell of a way to check though.

They were better ways of doing something but if it works, it works

He guessed right... at what cost~?

I mean there's other ways to check which twin is which
And this one falls into the category of: high risk, high reward

Steak said:

Did he guess before he checked?

I think this is the continuation of the strip before where he saw the twins changing. As you can see, sidetail-chan's underwear was the same with the one in previous strip, down to the pose in the small speech(?) bubble.

reaction of the stoic sister makes me wonder
is she jealous, or she's shocked

He got balls, gonna give him that.