As I read it this is an instance of or very closely related to taking the outside view though not by reflecting on how a neutral observer would see your thoughts but by ridiculing yourself.
For example I extended stereotypes about behaviour to myself: Of course you only need to use big words if your whole argument is to confuse the partner. Which made me realise that I use big words too much in everyday speech. Obviously the quality of an argument is independent of its presentation yet still the presentation matters.
Another example is when I wanted to change a specific behaviour with the same approach that failed in the past but this time it is different. The phrase "once a liar, always a liar" came to mind and I was motivated to try a different approach.
This one is fun. I think of it as self-caricaturing. Not trying to come up with a "straw man" exactly, but rather a comical/cynical oversimplification that still kinda fits. The goal is to compress it as much as possible while still having it be as accurate as possible. The more you can compress without losing much/the less nuances you lose, the more this self caricature tells you about yourself.
For example, I sometimes joke that I'm a redneck that doesn't want to believe he's a closeted hippie. It's a quite lossy caricature, obviously, but every...
One good way to ensure that your plans are robust is to strawman yourself. Look at your plan in the most critical, contemptuous light possible and come up with the obvious uncharitable insulting argument for why you will fail.
In many cases, the obvious uncharitable insulting argument will still be fundamentally correct.
If it is, your plan probably needs work. This technique seems to work not because it taps into some secret vault of wisdom (after all, making fun of things is easy), but because it is an elegant way to shift yourself into a critical mindset.
For instance, I recently came up with a complex plan to achieve one of my goals. Then I strawmanned myself; the strawman version of why this plan would fail was simply "large and complicated plans don't work." I thought about that for a moment, concluded "yep, large and complicated plans don't work," and came up with a simple, elegant plan to achieve the same ends.
You may ask "why didn't you just come up with a simple, elegant plan in the first place?" The answer is that elegance is hard. It's easier to add on special case after special case, not realizing how much complexity debt you've added. Strawmanning yourself is one way to safeguard against this risk, as well as many others.