The right way, the wrong way and the Company way...
After noticing a serious problem past 80 knots (blocked runway, fire or red warning, loss of control) we use a call of either 'Stop, stop, stop' or 'Continue' (as appropriate), with the decision to stop or go made by the P1.
Below 80 knots any abnormality would normally result in an automatic abort, so that we call '80 knots' on takeoff. The grey area is between 80 and V1, of course, since we are trained to take off once at or beyond V1, pitching up at least 8 degrees and then using V2 or more, up to 15 degrees pitch, as the target speed up to one thousand feet AGL.
It seems that we often get a problem in the sim that means we are almost at or just past V1 once we have recognised it and come up with a plan of action, so that we end up 'going'.
The PF remains the handling pilot on an abort up to the point where the left-seater has to take over since the ground-steering tiller is on the left side of the cockpit. That would be around 40 knots or so.
Then we have a little script stuck to the chart holder that details the drills for the left- and right-seaters following an emergency stop that is supposed to be memorised.