WWJD? and Kids

My son and daughter were fighting over the church envelope. Yes, in church. So my daughter had it last.

"WWJD?" I bent down and whispered in her ear.

She rolled her eyes and tossed the envelope to her brother.

"I don't think He'd roll his eyes." I said.

So I asked her brother the same question. WWJD? He was now in possession of the envelope. I just wanted to see what would happen.

He growled and tossed it back to his sister.

"I'm pretty sure He would not growl," I said. The envelope made it in the basket. Teachable moment captured or gone wrong? Your thoughts?