Please do not do this. It's not a serious offense, but it is rather distracting and unprofessional. If your book is more a gag story than anything serious, then it's fine and can provide good punchlines, but otherwise it's a terrible decision.

Let me try and explain why before I give an example.

When I read a story with a good plot I get absorbed into it. I'm not sitting in a chair with a phone in my hands, I'm side by side with the protagonists, running from bullets. It's a beautiful feeling and exactly what you want your readers to experience.

However, if there's some random bit of something shoved into the words then that effect is broken. Suddenly, I'm not in the middle of the action, I'm sitting in a chair staring at a string of words on a screen.

Now I'll give you your example, Rick and Morty style.

--
The two Ricks circled each other like beasts, each one bloodied and battered. Morty stood nervously to the side, his small hands (lol so kawaii!!1!) clutched nervously in front of him.

One of the Ricks snarled, his canines still bloody. "Shoot him, Morty, so we can go home, I-I'm gettin' tired of this."

The other one gave a short bark of laughter. "Wh-What are you, retarded? Like Morty would shoot his own Rick. Shoot him."

Morty looked worriedly from one Rick to another, glancing down occasionally to the gun that lay at his feet.

Tired of Morty's hesitation, one Rick lunged forward, rage in his blue (I said they were blue, right? Lol who knows) eyes.  Slamming against the other version of himself, the Rick sank his teeth into flesh, growling when he felt skin tear.

With a shout of pain, the bitten Rick went down, punching and kicking his assailant. "Dammit Morty, pick up the gun!"

Shaking, scared, Morty bent down and took the weapon in his hands.

--

*Dies in a fiery pit of death*

I hate this. I hate it so much it physically pains me. I don't care what you were thinking while writing that sentence, if it's really so important to you, put it in an Author's Note at the beginning or the end of the story, but please don't put it in the middle.