look up any word, like bae:
 
1.
You mention something that you are serious about, but don't ever follow through with it.
Dad: Lets go to on vacation (completely serious tone)
Daughter: OK WHERE!?
Dad: Las Vegas
Daughter: when?
Dad: maybe next year
...3 years later...
Daughter: You are a Mentional Liar!! For the last 3 years you said that we could go to Vegas!
by Crazy Kim May 12, 2010