Thing on Mumsnet that you’ve only ever encountered on Mumsnet (lighthearted...please don’t bowl in with “well I do that actually”...ignore or add one of your own!!
People not using fabric softener...appears that on MN people in their droves think it stinks and is devil juice (I don’t know anyone IRL who is so vehemently against it/gets a migraine from the smell?? Surely it’s not that strong?).
any sort of noise in your garden at any time-kids on a trampoline, playing a radio at a normal level, etc. Completely normal everywhere I’ve ever lived- a cardinal sin on MN! 