Underplum

When your ta-tas squirt out the bottom of your bra or swimsuit. You can see the underside of those plums!

Are you sure that swimsuit isn't too small? You got some underplums, girl.

Underplum by SoLucky Diva October 18, 2010

Underfluffies 

The fluffy feathers underneath the tails of birbs, covering their butts.

I showed you my underfluffies please respond

Underfluffies by ProjectOWL August 2, 2018

UnderLust 

An alternate universe of the game UnderTale containing almost everyone as lust filled monsters, and Mettaton EX as a shy talk show host.

UnderLust was created by nsfwshamecave on Tumblr.com

UnderLust by DepressingVoice16 June 28, 2016

underplumbed

(Adjective) describes a building or venue with inadequate plumbing or restroom facilities

(Verb: underplumb) To design or construct a building with inadequate restroom facilities or plumbing

(adjective) I’ve been waiting in line 30 minutes to use the toilet—this place is seriously underplumbed. (Verb) I have four teenagers, so don’t underplumb our new house with only one bathroom upstairs.

underplumbed by Dr. GlitterSparkles August 27, 2019

UnderBum 

1. When a female wears really short shorts and reveals the underside of her ass to passers by.

2. God's gift to ass men.

3. Also known as ass cleavage.

Adam: holy shit that chicks ass is hanging out! I think my dick just moved.

Craig: That my friend is some grade A UnderBum.

UnderBum by Hector the molester July 28, 2010

Underlust 

Underlust is Au, of undertale where soul falls into the underground but its not the monster's think. So they send it to W.D Gaster to research about the soul and Gaster finds out that, He can eject the lust in monster's, And then every monster in the underground is filled with lust, Including, Toriel, Sans, Papyrus, Undyne, Alphys, Mettaton/Happstablook and Asgore, And then Asriel is in this world, Toriel and Asgore Where happy about there child and then, Asriel dies and turns in to dust, Toriel and Asgore in Sadness, The ashes of Asriel go on a flower bed and the flowers (Which where roses) made Rose and then Happstablook and Alphys meet up in a Human-Fan-Club and Sence Happstablook likes being on stage Alphys decided to build, Happstablook a Robot body (That was a Sexual related body cause of course not) And Mettaton is on stage and got tons of fans, One night though everything changed, After a show Mettaton was Sexually Assaulted and Beaten by one of his "Fans" Sence Mettaton Was badly beaten Alphys Was trying to repair Mettaton, By doing Minor repairs, and giving him glasses. And is a tad-bit shy now. And a Teen falls into the Underground to soon realize that there is sexual reference's Every where. And that where we are now.
Weapons: Toriel/Old police Batons, Sans/A ripoff of Asriel's Swords, Papyrus/Fists, Undyne/Whip, The rest of these are fists.
I'll leave the rest of the detail's to you.

Guy 1:Man, underlust makes me look like a Virgin.
Guy 2: I like underlust, although it has a sour taste its actually pretty good.

Underlust by Etp445 (Unoffical) September 17, 2020

Undersummers

Undersummers are long legged panties specifically worn (and made to be seen) under dresses. These under garments are comfortable, elegant, and, unlike shapewear, practical in that it reduces chafing, discomfort from leg sweating, and eliminates panty lines. The product is designed by CarrieRae, and can be viewed at www.undersummers.com

Rather than uncomfortable shapewear beneath my dress, I am wearing my undersummers.

Undersummers by NewWorldDefined July 25, 2011