What's that supposed to mean?

Recently I observed this window sticker on an SUV ahead of me at a traffic light (sorry about the poor focus):

Oh, a single dad.  BTDT - I get it.

But after the light changed, and I was passing the SUV, I noticed that there were two adult males in the front seats.

Ruh-roh!  That's something different altogether.  [In unison]: "That's something different."

Now, there weren't any rainbows or unicorns or equal signs on the SUV, so maybe it was just coincidence.

But, these days, you never know.