Originally Posted by forstgump
Make him use a pump! Boom.
Yeah, this would do it.
You are the bigger of the two of you. You may not be able to physically control his trigger during a game, but you sure as anything can control his access to paint. Make him use only a pod or hopper per game, or similar.
At some point necessity will kick in and force him to be conservative.
Incidentally, it will also force him to actually play, rather than spray and pray.