It doesn't happen every time I stay sitting on the toilet for too long. But when I got visual aura or the weird hot piercing headache sensation (followed by high BP reading of 150/90), it's always after scrolling on the toilet for too long.

Lean over on one leg, tense that buttcheek and hold it to get the other side off the seat to restore bloodflow while you tense and release the muscles in the restoring side. Then, do the other. Much safer than standing up with dead legs in a room full of hard porcelain.

My girlfriend and her sister are like this. I'm travelling with them and sharing a hotel room and the pair of them can spend and hour and a half each shitting. It's very impressive. I'm fortunate that I'm constipated as fuck otherwise I'd have probably shit myself in desperation by now.