[gwd]

> "je ne sais pas"

"Je ne sais quoi", perhaps? https://en.wiktionary.org/wiki/je_ne_sais_quoi

"Je ne sais quoi" means "I don't know what"; "Je ne sais pas" just means "I don't know".

[andrewmcwatters]

It's funny you mention this, because it's effectively the same thing, mais si tu parles français, tu pourrais finir par dire l'un ou l'autre.