Ask HN: What are your reverse engineering skills?

I was wondering what the reverse engineering skills of people here in HN are.

From simple things like trying to mess with systems you assume to be based on regular expression, to more elaborate ones, down to more increasingly advanced techniques.

I'm not particularly interested in bit shaving stuff like hex editors or things like that, but if you're proud of something in that regard feel free to share.

Prompt engineering is quite outside this question (it seems that AI folk see themselves apart from other areas, so it's really not relevant to more principled reverse engineering techniques).