These are the custom octopus tentacle tights available for commission by Etsy shop tinkercast. The shop will paint the silicone tentacles whatever color you choose (complete with or without glitter finish) and aren't just limited to tights -- they're also available as fishnets (appropriate!) and leggings. I just sent the link to my girlfriend and asked if she wanted a pair and she said yes, so you KNOW what that means. "That you're still pretending you have a girlfriend." Bingo.
Keep going for a handful more shots of the under the sea possibilities.
Thanks again to K Diddie, who agrees under the sea *putting on cool guy snorkel mask* is the place to be.