My form of rubber ducking is starting to post a question on StackOverflow and realizing in the middle of typing the reason for the bug I've struggled with all day.

I suspect that's why SO posting rule are so strict, so people figure it out by writing the question :)
Happened several times to me too !

All. The. Time.
While in uni it would be I'd literally try tons of things, Google, SO and not find my solution.
Write a quick email to my Prof asking for help and then continue trying stuff. Usually ~5 mins later fix the problem and have to email again going I found it..PEBKAC