1. Used when one cannot seem to find the words they are looking for.
2. Used when another human being says something that causes others to feel uncomfortable and therefore become tongue-tied because they do not know what to say.
3. Used just whenever the hell you want to.
Stefanie: Shove some bananas down your pants!
Jennifer & Amie: Tongue-Tied Tarantula!
Also see Uncomfortable Cow and Awkward Turtle