Up! means stand up, there's a serious bump or a pinch flat opportunity
Granny ring! means ease off, we're dropping down a ring
Middle ring! means ease off and slow the pedaling, we're going up a ring. Middle to big and back doesn't need a warning.
Right signal! means stick out your right arm, and opposite for left
1, 2, 3, up! we count for standing
Accelerating! means pedal like hell, we're attacking, bridging, or just dropping these irritating fools.
I think that's all the warnings Captain gives.
Stoker:
Eating!
Drinking! as a warning that she's about to do same.
Otherwise, stoker doesn't give warnings. She just closes her eyes when we go too fast for her. Everything else is conversation, ride planning, etc.