Board Thread:News and Announcements/@comment-4224349-20150327195505/@comment-4655954-20150328173318

Genome Soldier86 wrote: I don't know if Say Uncle is canon, Matt Burnett likes to sometimes troll us with his tweets guys.

Anyways, I am now convinced that Uncle Grandpa using a bazooka and wearing a military helmet is a clear reference to Bazooka from GI Joe.

http://static.comicvine.com/uploads/original/7/79524/1429170-bazooka_00.jpg

XD The synopsis of the episode only further confirms that it is canon.