I don't trust stairs. They're always up to something.

Behind the Groan

What the Stairs Are Up To

Saying someone is “up to something” suggests secret or suspicious plans. Stairs are also literally used to go up to another level, so their ordinary purpose becomes evidence against them. Start with a serious, slightly wary tone, as if sharing a genuine warning. Leave a short pause after “stairs,” then give the explanation without stressing “up.” The straight delivery lets the familiar phrase sound normal before its physical meaning clicks into place.