In a slimy way, with a lot of slime or gooey stuff.
The word slimily makes people think of something gross or unpleasant.
Examples:
The frog moved slimily through the mud.
The snail slid slimily across the sidewalk.
The slimily creature left a trail behind it.
The slimily monster tried to give everyone a hug.
The slimily slime covered everything in the room.
The slimily snake slithered through the grass.