Once you go metal you won't want to settle means that, once you have sex with a robot, you won't want to settle for less. I'll take a gynoid robot over a human anytime! It seems that definitions like this don't get published because the Urban Dictionary is being run by rebublicans. REBUBLICANS! Examples of this are futurama and also fans of MLaaTR.
Fry:*doing lucy liu robot.*
Bender: What are you doing to that robot?
Fry: Hey! Once you go metal you won't want to settle.
Dude1:*Doing hot Jenny Wakeman robot*
Jenny Wakeman: Oh! You're soo good!
Dude1:I can't stop. This is way too good!

*5 hours later.*
Dude1 (still grinding the gynoid robot): Once you go metal you won't want to settle. Oh yes! Uh! Oh!
by TheCoolMeme May 25, 2012
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Basically, It's the future of sex. Once a sexy female robot comes around and you have sex with her, you won't want to settle for less. With robotic women: no STD, no pregnancy, no condom, no problem. The term "Once you go metal, you won't want to settle can be seen in a poster featuring Jenny Wakeman(XJ9). Jenny XJ9 is an attractive robot from the show "My Life as a Teenage Robot". It is after XJ9 got the 18 year old upgrade in rule 34 that the term, "once you go metal, you won't want to settle" began to be used. It get's hotter. Jenny wakeman is hot! Jenny XJ9 is sexy! Jenny Wakeman is from the show MLaaTR. I would pick Jenny XJ9 over a human any day.
Random Dude:*Jumps on Jenny the gynoid robot and has sex with her.*
Jenny Wakeman:*Does guy for 5 hours*
Random Dude:*Continues to have sex with Jenny XJ9.*
Random Dude:Oh yeah!
Jenny Wakeman: Wow!
Random Dude:I want more!
Jenny Wakeman:You can't be serious!
Random Dude: Yes! Uh! Oh! Energizer bunny:Once you go metal you won't want to settle.
by TheMatrixShrooms May 25, 2012
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do something not involving me, find a hobby, aka hop off my dick
I told my ex to get herself Go find you a white crayon and color a fucking zebra when she nagged me after the break up for her favorite thong she left at my residence.
by slimmmmemem August 10, 2010
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This means once you date a black man or women you never go back to dating other races.
Rebecca: I never knew betty was into black guys like that
Sam: After that one night stand with the black guy across the street shes never been the same
Rebecca: What happened?
Sam: She dates black guys only
Rebecca:Damnn
Sam: once you go black you never go back
by Aaaa214 November 20, 2019
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Vulgar idiom with American origin is typically used to imply that sexual activity with an African American or a black person is so enjoyable that one will exclusively seek out black partners in the future because of that.

Likely to harken back from taboos surrounding African Americans during the Antebellum period in United States history. During this period, large amounts of stereotypes existed around African Americans, many, also sexual. Racist ideas were held like that black men were considered to be animalistic and unable to control their sexual urges, which made having a romantic relationship with a black man, especially as a white woman, extremely taboo. All southern states had anti-miscegenation (anti-interracial marriage) laws, which weren’t abolished until June 12, 1967, by Federal law.

Many kinks surrounding black men specifically, like many kinks, are rooted in older taboos, which are now gone.
Ava said that since her last boyfriend, she has had an amazing sex life.”
“Well you know what they say.”
“Yeah, 'Once you go black, you never go back'.”
by CapeCodSpruce June 5, 2021
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Once a woman sleeps with a black man, no white man will be able to satisfy her, so she sleeps only with black men from then on. Usually because of their girth and size, but also because they appreciate more types of women in general and have better moves.
After she'd been with two black guys, she realized that once you go black, you never go back, because size really does matter.
by ksbunny July 27, 2012
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