More than 1 but less than 3. It's an alternative way to say "both" for people that are perceived to be smarter than others.
It is believed to have originated on the streets of Seattle as a special form of communication amongst seagulls.
Stali: "You better pick up that poop in the backyard or you will get the full treatment!"
Juanton: "Hand me bowlth of the poop bags. There is too much poop to fit in a single bag."
Dialect: a common regional quirk in the midwest. For some reason it seems like most St. Louisians pronounce it this way.
I had always thought StL used "television American english" but more people say "bowlth" than both in St. Louis and the surrounding counties.