To sniffle means to breathe in quickly and noisily, especially because you are crying or because you have a cold.
Sniffling can make people think of feeling sad or having a runny nose.
Examples:
She sniffled when she heard the sad news.
The little boy sniffled as he caught a cold.
I sniffled all day because I had a cold.
The puppy sniffled after being scolded.
He sniffled so loudly that everyone could hear him.
The baby sniffled and wiped her nose with a tissue.