When Penny was on pain meds and made Sheldon sing it in the round. Lol.
Great moral lessons in there nowadays.
And earlier in the same episode when Sheldon has to help her dress after she fell & dislocated her shoulder...
“Really, that top and those shorts?”
And the best, as he’s helping her put on her shirt, without looking:
Penny: “... Is that my shoulder?”
Sheldon: “It doesn’t feel like a shoulder.”
Penny: “Then maybe you should let it go...”
Mark