I think a lot of times one just has to be there to find something funny, but to contribute:
Marshall: Haha.
Ugh.
My own mother drew nudes...
Elizabeth: ...
Marshall: I was like, "Mom. Eww!" And she was like, "The human body is beautiful!"
Hippies.
Elizabeth: Yeah. That's exactly why people have sex in the dark.
Marshall: Haha.
Having sex in the dark might be hard...
What if you tripped and fell? It'd hurt and stuff. Like, "Oh hey, I'm going to go have sex. Ow! That hurt!"
No wonder so many old people die having sex... they're sensitive to falls as it is and the trip over some chia pet or something and... s'all she wrote.
Elizabeth: Haha.
Marshall: Oh yeah, they blame it on strokes and heart failure.
Uh-uh.
We all know it's the chia pets!!
Elizabeth: Haha. I don't think most people get up and walk around during sex, love.
Marshall: Well you have to walk from the light switch to the bed!
There are bound to be chia pets in the way!
Edit: This isn't the funniest thing anyone's ever said to me, just a funny thing said to me.