One time someone that used to know my family thought I was my dad's second wife. I also had this embarrassing moment with my mom. We were ordering food at a breakfast place. She was having a friendly chat with this middle aged woman. When it was time to order she asked "What do you want to order my love?" I answered and as I was walking to my seat that middle aged woman gave my mom a dirty look and stopped talking to her. I was wearing this backpack. It has rainbows, but I don't think it looks very gay pride.
This actually happened to me once, and it was really awkward. I was walking down the street with my dad with whom I'm pretty close, so he had an arm over my shoulder, and we were talking about our days (it was fairly late and we hadn't seen each other since about 7AM), and laughing a little bit, when suddenly a woman looks at my father with disgust, like he was doing something truly disgusting. We both guessed that woman must have thought we were a couple and was probably judging my father because of the evident age gap, tho it could have been something else as well. P.S. I think the backpack is fine, don't worry too much about it, if people want to find "proof" that you are gay, they are just going to over interpretate everything. Anyways, I do think it's weird that woman from the restaurant tought you and your mother were a couple just because she called you love, it's like Wtf? I have friends who call me love xD (tho, in Chile salesmen and saleswomen call you equivalents of "love", "honey" or "my dearest" all the time -if you are a girl, that is- and almost everyone in the street calls you "friend" when they want to adress you, so probably I'm just used to it).
Apparently one time my friend's coworker thought my Mom was my wife which was... interesting. He was a bagger at a grocery store my Mother and I went to once and I decided to go talk to him while the items my Mom was buying were being checked out and apparently after we left the grocery store, the cashier said something like: "Do you know why that woman's husband was being weirdly standoffish for how a husband would normally act?".
One time I went to the bus station with my mum, to pick the bus to another city. Now, my mum is very... expressive in her movements. We live in the same city but not under the same roof, so she was hugging me, kissing me on the cheek, telling me she missed me and calling me baby. Then she took me by the hand to get on the bus and we heard some teenage boys next to us giggling and whispering "lesbians, lesbians". My mum found it funny and started pretending we were a couple, jokingly, like "did you miss me babe" etc, and I was laughing hard. I think she finds it flattering that they thought she looked young enough to be my girlfriend.