Ready to teach a Bible lesson

I'm off to teach a Sunday School class of five (a young group, ages 3 to almost 8) for the first time. I had been teaching an older class, but now they are getting ready for confirmation. The lesson is from Samuel in the Old Testament.

When I come back, I may post something humorous that is not my usual G-rated fare. Would that be bad? Would I feel guilty? Especially after just guiding little children in Sunday School? I am unsure what to do.