n. pl. loon·i·ver·sa·ries
1. the date on which an event, such as being asked out, occurred in some previous month
2. the ridiculous
celebration of this
(shortened from Middle English lunatik, from Old French lunatique, from Latin lunaticus, from luna, moon + Latin vertere to turn)
Person A: I am going to celebrate my 3-month loonyversary with my sweetheart tonight.
Person B: You guys are so cute, it's sickening.