Grumpy-uglies

-This is not your case, Brenda. This is ours.

-Since when does the FBI care about high-school principals?

-A TSA Agent was fired upon!

-Driving the same type of car as my victim.
So, unless you think that the killer just really, really hates German cars,
then your TSA Agent was mistaken for my principal.

-Or your principal was mistaken for my TSA Agent.

-Well, now you're just being silly.

-Well, I'm not leaving.

-Well, you can stay here as long as you like, but it's still my murder.
And if you don't go home soon and get some rest,
you're gonna end up with a very bad case of the grumpy-uglies.

I don't understand what does it mean that sentence:

you're gonna end up with a very bad case of the grumpy-uglies.

thanks..