Forum Discussion
I have this too, but with a teen in Willow Creek (in Brook Bungalow). Traits are Self-assured & Bookworm, aspiration Bestselling Author. He's not been swimming - at all, ever - but gets this moodlet when walking down the hallway from his bedroom to the bathroom. Screenshot attached is the second time (he walked from the bed with the Zzz that haven't quite faded yet).
No mods/cc. All packs.
This just happened to my Conservationist Sim (Ocean Observer). He was on his way to snorkel in Mua Pel'am but had not reached the water yet.
After reading a lot of the resto of the comments, here is a list of traits and circumstances involving this particular Sim:
Summer (13 of 14), Sunny, Hot, Windy, Fitness Level 10, Self-Assured, Active, Child of the Ocean, Long Lived, Laid-Back, Marketable, Stoves and Grills Master, Great Storyteller, Antiseptic, Steel Bladder, Speed Cleaner, Heat Acclimation, Gym Rat, Waterproof Sim, and High Metabolism. Sim is wearing a swimsuit.
I hope that helps establish a possible pattern! I couldn't see one...