Simple way to pit plums
Not sure what you mean by "squeeze the pit out".  After you have cut the little guy in half, the pit is sitting exposed on the cut edge of one of the halves, and you squeeze it into a jar or something?  I guess getting the pit to disengage from the plum flesh is messy &amp; time consuming (?) .
 
I have done this a more wasteful way in the past by slicing twice on the flat sides of the seed, then using the two outer cut off (seedless) slices, and even cutting off some of the flesh of the center section (containing the seed) if I was feeling frugal, .... otherwise discarding the whole center slice.  Depends on how wonderful your plums are.  Mine were considered "junk fruit" by the tree's owner.

See diagram: you start with "A", make your cuts, and wind up with two "B"s and a "C".

Anyway, it is still pretty labor intensive, but pretty quick once I got the hang of it.