Although I don't play on BLU, this works well:
Step 1: Hope the RED and BLU team has a bunch of players with mics (Servers with high player counts, like 24+ players).
Step 2: Make it out of cell rebel day, lava day, and some other day like no taunt day.
Step 3: By this point, everyone is talking on their mics, so end ONE of the days.
Step 4: If no one asked for a repeat, wait like 30ish seconds (As some people may have actually ran out of the cells, making them KOS). During this time, a lot of people will be talking and people start to forget days.
Step 5: After waiting for a bit, end the random day added, like no taunt day.
Step 6: Some people may have fallen for that, but not everyone. End the other day after some time (Either lava day or out of cell rebel day, depending on what day was originally removed).
Step 7: You can expect a lot of REDS to still be in their cells, as a bunch of them forgot the days and they can't ask for days anymore.
Step 8: Level up your stranges.