It wasn’t until I actually typed this in myself, and read it (and said it out loud to myself) half a dozen times that I finally understood this.
Apparently “buffalo” is a term to bully, I’ve never heard it before, but in that context, buffalos should really stop buffaloing Buffalo buffalos, or they themselves will find themselves the subject of Buffalo buffalos buffaloing Buffalo buffalos… Reminds me of a Thai tongue twister, but that’s subject to another post.