When you have met someone on the internet/through a dating site and when you meet them they turn out to not actually be a dog like the snapchat filter made you think.
"Hey bro, how did the date go?"
"ahhh man, it sucked. I met her at Taco Bell and she wasn't even a dog. On the picture she sent me on Snapchat she had floppy ears and a dog nose. She totally dogfish-ed me dude"