If you thought a single leaf wasn't enough of a costume, here we have a more traditional interpretation of Poison Ivy, as cosplayed by our favorite freckled futa. This costume may not cover much skin, especially when Becca gets her hands on Lindsey, but if anyone asks, Lindsey is planning to say she's cosplaying a rule 34 futanari Ivy, because plants are hermaphroditic, get it?
Becca's Suicide Squad Harley may not look too original on first glance, until you realize she's using Lindsey's cock as her baseball bat to complete her outfit. That should be more apparent in the color version when you'll see "Good Night" written on it with Becca's lipstick.
Lindsey is, at the present point in the story, much too shy to consider wearing this out, but perhaps one day... Becca could convince Lindsey to show up at a costume party dressed this way, ring the doorbell, and strike a pose. Opening your front door to be greeted by this flexing pair of troublemakers would be quite a sight!
Here's an extra version without the vines on Lindsey's costume: