Hastüt is an exclamation, similar to "Oh My!". It is usually used when tired, or confused.
Pronunciation: Refer google for the pronunciation of "ü"
Ha in Hastüt is pronounced "Huh" without the h in the end. (not "hoo" just "huh")
Mom: Wake up Rizeen
Rizeen: Hastüt! (Meaning, Rizeen is too tired to wake up)
When something is unfunny, but the something is trying to be funny but is not.
Blud is tryna become Master Oogwgay with that joke.