how do you tell your kids "mum and dad have a regular overnight away" without actively lying

F38 dh 40, kids 7 and 10, weve been doing one overnight a month (kids at the grandparents, us at a hotel) for about a year now and the kids have started clocking it as a regular thing. fair enough, it IS a regular thing. the older one asked last week "why do you and dad have a sleepover every month". which... great question, mate. we'd previously been kind of vague, "oh mum and dad need a break sometimes", "its grown ups time". which worked when they were younger and "grown ups time" meant nothing to them. now 10yo is sharp enough to be like, ok but what do you DO, you cant possibly need a hotel for a break, our house has beds. i really really really do not want to lie to my own kids in a way that will eventually need to be unlied. like the in-laws and the sitter, fine, theyre adults and the relationship doesnt depend on truth. with my kids, anything i tell them now is a foundation for the relationship later, and i dont want there to be some big "oh actually it was always different than what we said" reveal when theyre 18. so. is there a vague-but-true framing that works?? "mum and dad like having time together where we can stay up late and dance" — is that enough?? "we go to grown up parties where we know our friends" — too suggestive?? how have other ppl threaded this needle. i feel like i need a sentence i can repeat for the next 8 years that ages with the kid without ever needing to be retconned.