1) A failed attempt to insert a penis into a vagina (or twat). In other words: the "serve" falls outside the "service box".
Twault=(Twat+Fault)-See "Fault" in regards to tennis.
2) When a male's erect penis gets caught on the vaginal surface (usually upon a failed insertion attempt or correcting for slipping out during intercourse) causing a pole vaulting type of phenomenon that the male would endure.
3) Twault=Twat+Vault (e.g., a bank vault. Only instead of a bank, it's a twat.): When a woman withholds the release of sex to her partner, much like Disney does with its movies. The sex is then said to be "locked in the twault". See Disney Vault for clarification.
Dude 1: Hey, did you finally score last night with that chick?
Dude 2: No. I twaulted too many times, and got disqualified.
Girl/Woman: Oh, my! Are you OK?
Male: No! I think I fractured my penis after I twaulted... Yeah, it's bent. Definitely fractured my penis.
Male Friend: Wanna go out tonight? Cruise for Chicks?
You: I probably should... The GF has all the sex locked up in her twault.
The age where you are between a teen and an adult.
The age between 18-21 is considered to be a twault.