Philadelphia Eagles to Fans: Bring Your Dog Masks!!!

Going to the Eagles playoff game this weekend? Better hit the costume shop first ...

The team is encouraging fans to bring dog masks to Lincoln Financial Field in Philly on Sunday -- to keep the whole "underdog" theme going as they face the Vikings.

Of course, Chris Long essentially started the dog mask thing by rocking a German Shepherd head after they beat the Falcons this weekend.

Now, the team has sent a message to fans -- "Doggone it, you better believe dog masks will be allowed at @LFFStadium this weekend. Just make sure to take them off when you go through security."