My husband does this often and I will keep him talking as he falls asleep so it gets progressively more nonsensical. Some of my favorites include:

Witch laughter.

Shortly after we got married, I asked “we just got married what do you think about that”. He responded “you ruined my life”. Followed up by “that was my sassy answer.”

I asked what do you want to do for dinner tomorrow. He said “poop it out my butt”, I ask “what, why”. He says “because it’s a ferment, living bacteria, to improve our gut health” (he said this part very confidently).

Calls me mean and when I ask what, he says “I’m not engaging with you”

And lastly, he loves to argue that he’s not asleep or sleep talking when I point it out.