When I was a kid, my mom bought regular kids' one-piece pajamas for me and cut the seat out. She called these my "Special Pajamas" or "Punishment Pajamas". I always had a pair from age 3 to age 12.
When I misbehaved, she'd tell me to go to my room, get undressed, and put on my Special Pajamas, and wait for her to come in. She'd make me wait quite a while (that was part of the punishment) and I never knew whether she'd be bringing in the hairbrush, the paddle, or the strap.
Whatever instrument she chose, I was nervous and scared, and my buttocks were bare and ready to go over her knee (hairbrush) or over the table (paddle or strap). I'd have to leave my Punishment Pajamas on and stand in the corner afterward with me red sore buttocks on display till she told me enough.
As a little girl, I once had some panties that said "Remove panties before spanking". I don't know where my mother got them. Everyone but me thought they were cute.