Get with your partner between half innings and mention something like "jeez, this game sure is dragging along, don't you think?" Something to give your partner a clue.
As BU, you could also get those fielders moving by saying something like, "here we go, now... hustle in, hustle out..." At the same time, lead by example. Make sure that you're also hustling along with them into your between-inning holding zone and your BU position (A, B or C). Players and coaches can be lemmings in that fashion.
I don't want to do anything that would appear to be stepping on the PU's toes, but somebody's got to get the game moving.