chub in the scrub
In a hospital setting, it is when a male wearing scrubs is suddenly overwhelmed with an erection, largely due to a attractive female employee displaying her attributes on purpose or otherwise.
"Did you see that chick on 4 west?"
"Yeah! She's smokin', I got a chub in the scrub when she dropped her pen and bent over to pick it up!"
"Yeah! She's smokin', I got a chub in the scrub when she dropped her pen and bent over to pick it up!"