OC is legal here in WI (for another few weeks, it's the only legal way to carry), and when I'm in one of the few places we're not allowed to carry, I just take the pistol out (sometimes the spare magazine too) & leave the holster on my belt.
That's when I'm not intending to make a point, though at school it has sparked a few discussions, all positive. Most of my classmates either don't notice (which would be hard) or don't say anything, & a few have been genuinely interested in why I carry & what some of the laws are.
Today I went to a meeting about our new cc bill, & since it was in a prohibited place I OC'd an orange plastic training pistol, & cc'd another one.
That's when I'm trying to make a point.
If anyone (official) ever says boo to me about an empty holster at school, I'll add the orange training pistol.