It was apparently very practical, especially for when nature called!
The actress said of the dress:
"It fits, it’s comfortable and it’s easy to pee in. You just lift, hoist and do a couple squats!"
Ha! That's quite the visual!
And fiance Justin Theroux loved it for being "Valentino red," and probably appreciated not having to lend a hand for when his better half had to go to the ladies' room.
Good thinking, Jen!
[Image via Adriana M. Barraza/WENN.]