That used to happen to me alot when I'd cross my legs.
Like I'd get weird twitch-like spasms just like if my eye were twitching or something.
And just like you, I'd uncross them, and it'd stop.
I'm sitting there all wtf-like, and so eventually I just stopped crossing my legs cuz it got annoying after a while.
It'd happen to me almost every single time.
Weird.
lol
Oh my gosh sometimes I get the weirdest gas bubbles and it honestly reminds me of when Aspen used to kick me.
it could be muscle spasms, or gas? I get those too but it is usually one of the 2 I listed above. I have poor circulation as it is, so crossing my legs for long periods of time causes me to have spasms.