The Nuck is when you're getting ready to do the dirty to a girl's asshole and instead of just sticking two fingers in there, you stick all 4 up to your big knuckles.
Furthermore, the double Nuck is when you use both hands up to your big knuckles.
I was with this ho last night and I was poundin' her for hours when I decided I wanted somma that sweet ass, so I nuck'd her!
2: To position one's self to sexually penetrate his partner, specifically in a back-entrance position, otherwise known as 'doggy-style' (common slang).
4: When a stallion (a male horse) positions itself on top of the female horse, just prior to breeding. This pre-penetration act is known as nucking.
In a 'doggy-style' position, the male is typically standing on his two legs and supporting himself with one of his arms either on the floor or the female's back. Meanwhile, he is stabilizing himself by adjusting his footing/balance, if you can picture that. The male is nucking, getting ready to penetrate the female. It is the most natural, primitive state of sexual intercourse between male and female. (i.e., as the beast nucked in preparation for copulation, the excruciating anticipation of the pleasure awaiting him caused his erection to jump and ooze with pre-ejaculate fluid.)
A Baltimore slang that can mean whatever you want it to mean. Typically used to refer to your homies. Coined by the famous Baltimore barber Bippleyipsnip.