People who tell me about goats - what they like and how I should look after them - when they actually know nothing about goats. We have a friend who used to do that on the strength of his son-in-law had goats, until another ex-goatkeeper agreed with what I said. MInd you, it could be something to do with the other ex-goatkeeper being a man.
And my mother, when I tell here something to do with medical matters, gardening, anything really, saying she'll ask my brother on the strength of his getting a degree in biology 36 years ago. If I object she says, "Well, he has got a degree you know." and when I say, "So have I and a Masters and a teaching qualification," tells me, "But his is in biology."