When i'm sweating bullets and there's a breeze, i will unzip my jersey. I don't do it all the way since I don't want it "fluttering" since my cellphone is in the middle pocket (and it hides my gut).
I have had people ask what the strap is so I tell them it's heart rate monitor so I know if i'm going have a stroke.
I don't have a "dad-bod", it's more of a "granddad-bod".