Homer is about to give Bart exactly what he wants

this isnt dark humour (unless I just don't get it)

Bart Simpson is singing "Take My Breath Away", and Homer Simpson is saying "Gladly! You Know I Can", because he can literally take Bart's breath away by strangling/choking Bart.

Here's the song "Take My Breath Away" by Berlin, in case you're interested:

https://www.youtube.com/watch?v=Bx51eegLTY8

yeah i know the song. I guess I did know the joke. But I didn't find it as dark humour.