I was having a bad day yesterday and wrote extremely provocative things on math overflow, math stack exchange, and philosophy stack exchange. I am worried that I could face a consequence. I have decided to stop writing inappropriate things. But just out of curiosity, is it possible to get simultaneously suspended from all stack exchange Q & A websites?
Yes, it's called a network-wide suspension and it can only be applied by staff. It is used very sparingly for users who consistently cause problems on multiple sites. But also because once it's applied, it's rather difficult to remove the suspension. So we like to make sure that the user really does need that level of suspension, as they'll have to actually serve that full length. We generally wouldn't use this for someone who's never been suspended before unless they're obviously attempting to be a troll.
Yes, network-wide suspensions are a thing, although it's reasonably rare for them to be necessary.