What does US and UK mean?

unwashed sage

uphill saloon

useable strife

utopian society

utensil speller

untutored kid

upfront knavery

upscale knife

upper kinship

ultimate keen

U.S.

-Unidentified Space

-Unmentioned Sacrifice

-Underhand Stroke

-Underachieved Slacker

-Useless Slander

U.K.

-Untidy Kitchen

-Understanding Kate

-Unified Knowledge

-Unraveled Knitting

There were some old ones in french :

- for USSR (URSS in french) = Union Ratatinée de Saucisson Sec meaning union made of dried sausage

- for USA : Union des Suppositoires Atomiques meaning Union for Atomic Suppository

But cold war is finished now, there remains :

- for SNCF (French railway - Société Nationale des Chemins de Fer) : Savoir Nager Comme Fernandel meaning you shall swim like french actor Fernandel

- for RATP (Paris Subway - Régie Autonome des Transports Parisiens) : Rentre Avec Tes Pieds meaning "Come back home with your feet" because they often are on strike.

Sorry i have nothing newer, and i know no other one neither about UK.

US:

Unattended Sponge

Unavoidable Stooge

Umbelical Sushi

Ugandan Silverfish

UK:

Uneaten K Y

Unsucked ****

Usual K-Mart

Ultimate Sh*t

Unique Kids

US- urban streetwalker

UK- Urban Killer

US- ugly stripper

UK- unfit kitchen

US: Utterly stupid

UK: Under knickers

United States and United Kingdom would be my first guess..

ugly sacks

uber stupid

unintentional karate

undressed stripper

Undressed killer

lol