Frog in My Throat

I recently had a cold and lost my voice. I'm still trying to recover it.

Today, one of my 2nd grade fluency boys asked me, "um, do you have a sore throat? or is something wrong with your voice box?"

In another group, a 2nd grader said to me, "What happened? Do you have a frog in your throat?" "Yes, I do have a frog in my throat."

"A real frog?" says Alex.

"No, not a real frog."

"Well, why did he say you have a frog in your throat?"

"It's just an expression. Something we say when our voice sounds scratchy."

"Well, I don't get it. Why a frog?"