Guillotine is the 96th level of the Story Mode (World 9, Stage 6) and the 46th level of the Challenge Mode in Expert.
This is a level in which your monkey ball is supposed to roll up ramps that become longer and longer in a semi-circle. A spinning rod holds two platforms that wipe across the top of the ramps. Therefore, if you don't make it over the ramp near it's edge, there is a high chance that you will be knocked off the edge of the course with the one of two "guillotines."
The time limit of this level is 60 seconds.
The difficulty of this level is advanced compared to an average player.
Standard Strategy: As soon as the level starts, go as fast as you can through the right side of the pathway without falling off until you reach the first ramp, you need to reach the first ramp with enough speed so you can pass through it as soon as possible or as else the guillotine will knock you off if you don't do it quick enough, then, slow down and progressively move while you keep track of when the guillotine passes and keeping track of your speed so you can pass the ramps. The last one is harder than the first ones because it is so large you need strict timing and enough speed to pass before the guillotine hits you.
Strategy for Speedrunners: There is a strategy that involves with hitting the guillotine on purpose at certain angle so you get knocked off to the side where the goal is located. I don't know the technical details about it but pause buffering may be useful for this.