Do you take it before you step on stage to get an epic pump and glycogen supercompensation?
Some do but very dangerous, contest day you are already at the verge of falling on your face, added slin would just increase the danger but it would process the carb load and the fat load to increase muscle volume almost instantly.
the problem here is you have to drink water post slin so you don't get nauseous so unless you are super dry it might not be a good idea.