Choosing a child at the park

When I was watching my daughter at the park earlier, another parent asked a man, "Which one is yours?" and he replied, "I'm still choosing." She looked horrified.

Explanation

Experiment

The humor comes from the man's absurdly inappropriate response to a simple question. Instead of stating which child is his, he says he's "still choosing", as if they were objects or pets. This implies he might be choosing a child that is not his own, which makes the other parent feel horrified.