Back 4 Blood has some excellent references buried within its new beta.
Just below, you can see a Twitter user chronicling a selection of the Back 4 Blood in-game sprays, as of earlier today on August 6. It turns out that these sprays are perhaps not-so-subtle references to things such as Roll Safe, aka the guy tapping head meme, The Muppets, and other pop culture cornerstones, like Nick Young looking incredibly confused.