To snuffle means to breathe noisily because of having a stuffy nose. Also, it can mean to make a noise like that.
Snuffling can make people think of being sick or having a cold.
Examples:
When I have a cold, I snuffle a lot.
The little dog snuffled around in the garden.
She snuffled all night because she was sick.
The bear snuffled as it looked for food.
I snuffle so loudly that the whole world can hear me!
The baby snuffled and snuggled into her blanket.