ノーパン
nōpan

Noun

1. panty-less; wearing no underwear

下着 したぎ いに くんだよ。お まえ、まだノーパンだろうが。
shitagio kaini iku ndayo. omae mada nōpandarōga.
We're going to buy underwear. You're still not wearing underpants, are you?

From English "no panties"