Here's what I know...
(1) People gravitate towards happy people, not miserable sourpusses so if you can't get rid of the sourpuss, stay home.
(2) No one wants to hear your tales of woe; everyone has their own Bernie Madoff story, no one wants to get depressed by yours.
(3) Men know that women get their period once a month, but they certainly don't want to hear about the fact that you have it now and it's put you in a bad mood. This is poor judgment on your part and just icky.
(4) If you are in a bad mood when you are out, no one will want to be around you because they can feel it. Trust me, they can.
(5) A bad mood rises to your eyes. If your eyes can't, then the smile on your face doesn't matter.
(6) It's okay to have a night of downtime; it might re-energize you for next time!