Putting lubricant or jello into a Dutch bros child sized cup and masturbating with it. Commonly done by males occasionally done with women but putting lubricant on the outside and inserting into the vagina.
"Oh no this Dutch bros cup has lube inside... he must have used it for the slippery Dutch again"
whilst in sexual intercourse from behind, your partner wears a snorkel to prevent suffocation caused by you jamming their head into the pillow. One proceeds to then pull out and ejaculate into the snorkel. Thus completing the slippery fisherman