Batty Sweat
Batty Sweat is when your body is sweating so much that your arse hole produces its own sweat, so when you sit down on a chair you can see the outline of your arse cheeks.
Me: Im so hot
Dave: Why don't you sit down in the shade
Me: No I have Batty Sweat
Dave: Why don't you sit down in the shade
Me: No I have Batty Sweat