My child is so funny

Last night I was in the kitchen fixing Darrius a protein shake. Yes, he drinks protein shakes. Darrius is trying to get buff. Ha ha! While I'm fixing his shake, he walks into the kitchen and tells me that his workouts are starting to work.

D: Mom, look at my shoulders. They are getting bigger.
Me: Really? Let me see. Stand still.
D: You see how big my shoulders are? It's from my workouts.

I continue to stare at him. And then I realize something. Only one of his shoulders is bigger. It's bigger and red.

Me: Ummm, D, your shoulder isn't big from working out. It's swollen from the tetanus shot you got yesterday.
D: It is?
Me: Yeah. Is it sore?
D: It's a little sore.
Me: Take some Tylenol and put some ice on it.
D: That's ok. I'm fine. It doesn't hurt that bad.
Me: Can you move your arm without much pain?
D: Yeah see it's fine.
Me: If it starts hurting, let me know.
D: Ok.
D: Man, I was showing my friends today at school how my workouts are making me bigger. I was showing off my shoulders and everything. Flexing and showing my muscles.
Me: Well I guess tomorrow you'll have to tell them your shoulder is bigger not because of your workouts but because of your tetanus vaccination.
D: Yeah I guess. This sucks. I thought I was getting some muscle.

He then walks out of the kitchen, protein shake in hand, head hanging low.