Mental dating 

Dating a celebrity whom you have a huge crush on in your head since you do not stand a chance to actually date him/her. Tweeting numerously at the particular celebrity's account to get his/her attention is the best way to know if one is mentally dating a celebrity.

- So wassup with you? You married or something?
- No. but I'm mental dating a celebrity.

Mental dating by Mas Swagengen September 28, 2011

Mentalbating 

The act of mentally envisioning erotic acts and/or situations in public after viewing an erotic image ie a sexy advertisement or an attractive woman.

Alex: dude, I saw that guy looking at the sports illustrated swimsuit magazine in the gardening section at the bookstore
Kyle: Yeah, he was totally mentalbating

Mentalbating by KSTORMY April 5, 2010

Mentalating 

Expressive feeling related to the mind, cause: mental ventilation. To explain the thought process via feelings about thoughts.

She was feeling so good with her boyfriend, she could say anything with ease, as freely as a new born bird with thoughts she was hyper-mentalating.

Mentalating by SunnyJo July 4, 2010