I think there's words with dual meanings and words that are misused. Genius is often misused to an extent and often used as terms for derision. For example "Daddy I learned to tie my shoes today" - *sarcastic* "genius".
A lot of (Afro) American terms which due to the nature of media have become used a lot in British language.
* Flossing - showing off, also meaning cleaning.
* Booty - also meaning pirate's treasure.
* Dank - now largely used to describe strong weed or hoppy beer, but also dingy.
Other terms:
* Piracy\Pirates - not really used in the literal sense these days.
* Apple - a brand name as well as the fruit.
* Fluff - often means something which is light on content. "The works of Candace Bushell are just fluff to please housewives"
* Flip - to lose one's temper, not sure how long this has been used for, probably decades as well as physically moving something.
* Killing - as in make a killing. More an idiom.
* Sick - pretty obvious, good as well as unwell.
* Turn Over has a dual meaning as in "I turned over the wanker's house last week" - I'm guessing this has been around since the 70s though.
Sex Words:
*Motorboating
* Watersports - depends on the context.
* Faggot - not really used to describe a meat product that often, also a general slur.
* Babygirl?, Daddy?, Mommy?
* Vanilla
* Hardcore
* Being\getting pressed - as in getting fucked hard.