Stands for 'sorry my internet failed' when instant messaging with a friend over the internet. Most commonly used after the user rejoins the conversation, having lost internet connection for a short while beforehand due to their shitty internet service provider.
"how's everything going?"
*other person is offline*
*other person comes back online*
or used as a verb:
- my internet smiffed
- i have a feeling i'm going to smif in a moment, my internet's been dodgy all day!