Popped the fill plug off my rear axle to see if I was low and this chocolate brown milkshake thick ooze poured out of the diff cover.

Theories:

1) someone shit in my diff.

Or

2) the rear diff spent some quality time in a lake and nobody changed the fluid after.

Or

3) someone literally took a massive runny dump in my diff.

Side-note. Image upload on mobile appears to be broken.