Either a friend or a stranger.
Microaggressions are small, subtle yet apparent insults that occur either intentionally or unintentionally and communicate a hidden hostility or disapproval towards someone. They may or may not be aware they are doing this (subconscious) - but the slips happen if you know what to look for.
Two examples that happened to me recently:
First one -- I was out in guy mode with a good friend, a CIS woman we'll call Wendy. She's somewhat aware of my trans proclivities. Anyway we where getting her car diagnosed at a private house garage. They had a golden retriever on the lawn to which we where petting. Wendy asked if it was a boy or a girl, to which the owner replied from inside the garage "girl". Then she said quietly with me there, "oh! so you're his kind of dog". That was a micro-aggression.
Second -- I needed a pair of sharp eyebrow tweezers so I went to a beauty supply store to pick one up. I was dressed in guy mode, hair long (and well moisturized I might add

) around my shoulders so I looked like an effeminate andro guy. At the counter to pay - the cashier gal seemed to pause giving me a subtle quick 2nd take. I noticed her robotic rhythm of straight forward scanning the item and finishing the exchange seemed go off track. Like her mind went off course (or she was thinking about something). She hands me my change with seemingly brusque body language then looked away with an aloof look on her face.
These are micro-aggressions.