Looking at myself in a mirror and, especially, watching videos of myself (I only discovered this quite recently when smart-phones became ubiquitous.)
The mirror thing doesn't bother me too much, and often makes me giggle, as I've always had that weirdness; my brain seems to get a bit confused about whether it's controlling my real body or the reflection, and then gets flummoxed when my motions don't quite match what I intended. Watching video of myself is really freaky, though; I recognise my own appearance, but my facial expressions, posture, gait, gestures, prosody, etc. just don't match how I imagine myself in my head at all - it's like watching a replica of myself which has been very badly programmed to copy my behaviour.
_________________
When you are fighting an invisible monster, first throw a bucket of paint over it.