A special bench...

That is very strange!

It is a human body :-)

In rather an uncomfortable position!

A very good notice. In Slavic languages, like Czech or Slovak language, an idiom "to sit on somebody" means "to put somebody in very uncomfortable situation".

That's interesting! A similar idiom in English, to sit on or "squash" somebody is to deflate his ego, scorn his idea or "cut him down to size" (another idiom!)

In our meaning, it is not to deflate his ego (I pushed his hat off, is better expression for this) but to bully. To sit on somebody is to bully him/her.

Idioms are fascinating. "Push his hat off" is excellent!