Millie, baptism song would explain the "we" and "them" in the wording. And the dirge-like song would seem appropriate for the crowd to be singing as the baptismal victims have said their "yes"s and head off with their towels and modest bathing suits to change.
But for a baptismal song, shouldn't the lyrics be more like:
"Now we watch them dunked in the pool,
Gotta get this done before they start public school!
For 'Christian' parents, we have this tip:
These kids act up? We disfellowship!"