The Avengers Blu-Ray is pretty sparse on extra features, but...it still pleases me in a simple reptilian way.
No original content contained herein and no ownership implied; all material ganked from the farthest reaches of the Internets. If unsatisfied with picspam, please return unused portion of post for a full refund. Use only as directed. If symptoms persist, see a doctor. For a free written transcript, hit CTRL-P. And I could go without ever hearing about Frankenweenie ever ever again. And it's not even out yet.
It's a squirrel knot, and apparently it's a recorded phenomenon. There was another link I found documenting it further (baby squirrels get their tails tangled), but it featured pictures of posthumous squirrels, so...I closed that tab pretty quickly.