it was a hot day and I had my shirt off
I guess they are trying to get your attention to them? I never said this to a guy that works out xD But in my mind...they are I guess trying to have their good sense come out. I dunnoh.
Sounds like the girl is flirting...never used that line on a guy myself but i have had friends that said it. It's not a bad thing. I would take it as a compliment. :)
I understand it is a polite way of saying:
"Would you be kind enough to use a double strength antiperspirant / deodorant?