Hmmm... I don't think he says any bad wrods.
angelene thought he said Jack*ss, but SpongeBlob explained it as
"Soo (like "sew" or "sue") takka (like "talk a") jawkassa (like "jaw cost a")
It does sound like jack*$$ a little bit. That's funny. Good catch, Angelene."
I haven't actually watched the episode in a while though, so I wouldn't know for sure...