This is a local phrase used mostly by Nigerian millennials as witty remarks, to describe a scenario where one is tired or gives up on a situation or thing.
In a nutshell, it's used to describe a scenario where something is incapable of being solved or accomplished.
Since my last relationship, my life has been nothing but peace at its finest. Ah, I can't coman go and kee mysef.
After cooking the meals and tucking the kids to bed by 10pm, you still expect me to do your laundry? I can't coman go and kee mysef o.
Coman usually used to describe someone with overly hairy and moist testicles that dangle at a 62° angle from their inner tighe.
Guy: will you shift my friend
Girl: let me see his junk
Girl 2: ew he looks like a Coman.