Chief Keef is a furry, and I have proof:

In his hit song "Love Sosa" there is a line where he says "He six double-o boy", which can be easily misheard as "E six double oh boy" in a reference to the popular furry website e621, where it can be interpreted as him seeing e62 and then going "oh boy!"

Shortly after in the song he also says "She gon' clap for Sosa, He gon' clap for Sosa" in a reference to the fact that a large majority of the furry fandom is often a sexuality other than straight, and as some people would argue, often bisexual. This may also mean that Chief Keef is bisexual too.

If we look back to earlier in the song, he spits the line "You can meet my llama" meaning his fursona is clearly a llama. Replaying the song from the start, there is a small rant from him where he mentions "My boy a BD on ♥♥♥♥♥♥♥ Lamron and them" where BD references the popular furry sex toy manufacturer Bad Dragon (As of writing this, there has never been a toy calle Lamron, however Chief Keef may collaborate with Bad Dragon in the future to make a llama phallus with that name.)

This concludes my evidence that Chief Keef is a furry, I hope you enjoyed reading.