Uh-oh, I smell the start of a storyline!

My guesses are... blue food coloring... umm... toilet cleaner? Ooh, Era* is blue too... I guess there aren't really many blue-coloring or staining household substances...
Then again, blue food coloring can be added to many things. Water. Ms. Mudd's coffee...
Hmm, and Ozy's hat is nowhere to be found! Strange... he seems not to be wearing it at all today!... I guess it's too warm?

* - A laundry detergent.
[Edit: Blueberries! Blueberry flavored juice... Blueberry Jello!]