Guys, here is a simple rule for the guy who works in an office that has gray shirt-tuck area:
If wearing button ups, and your office is formal enough where the top button of your shirt has to be buttoned(not the collar, but the top non-collar button), you should probably tuck. If not, let it loose.
If you are wearing anything that doesn't fully button, tucking would be Fake Sugar Dick (WARNING, NOT THE REAL SUGAR DICK!).