The superlative form of 'slick', meaning very smooth and slippery.
This word can make people think of things that are very smooth, like ice or oil.
Examples:
The slickest ice is the most dangerous.
The slickest oil makes the car go fast.
The slickest floor is the hardest to walk on.
The slickest banana peel made him slip and fall!
The slickest slide in the park is so fast, it's like flying!
The slickest snake slid silently through the grass.