-R-

'Randy':
    Horny. 
(Randy is a male name [only] in the USA)

Rasher (bacon):
    Slice

Redundant:
    Laid-Off
("Jack was laid-off last week" "What a shame!")

Register:
    Roster

Repeat (TV):
    Re-run

Return (journey):
    Round-Trip

Reverse (a car, etc.):
    Back-Up

Reverse-Charges:
   Collect-Call

Revision:
   Study, Cram

Ring (on phone):
    Call

'Roger':
    Sex, 'Get Laid'
(That particular slang word only means a man's name is the U.S.)

Roundabout, Island:
    Traffic Circle 
(And thankfully they are few and far between in the USA!)

Row:
   Argue, Fight, Quarrel
("Jan and Mike had a big fight last night and Jan walked out on him")

Rubber:
    Eraser

Rubbish (refuse):
    Garbage, Trash

Rubbish, Nonsense:
   Baloney, Crap, Bull****

-S-

Sack (get the sack):
    Fired
("Johnny got fired last week for calling his boss a 'douche bag' ")

S.A.E:
    S.A.S.E (self addressed stamped envelope)

Saloon (car):
    Sedan

Sand Pit (Children's):
   Sand Box

Sello Tape:
    Scotch Tape

Semi-Detached:
    Duplex

Semi-Skimmed Milk:
   Lowfat, "2%"

Serviette, Napkin:
    Napkin

Settee, Sofa:
   Sofa, Couch

'Shag':
    Not used 
(although possibly a bit better known now after 'Austin Powers!'). Numerous other slang words used; too numerous to mention

Shandy:
    Unheard of

Shaving Foam:
    Shaving Cream

Shop:
    Store

'Shop','Grass':
    'Nark','Tattle'

Shopping Trolley:
    Shopping Cart

Silencer (car):
    Muffler

'Skidoo':
    Snowmobile

Single Ticket:
    One-Way

Smack:
    Spank

Smart (dressed):
    Sharp

Solicitor:
    Lawyer, Attorney

Sorbet:
    Sherbert

Skip:
   Dumpster

Sledge:
    Sled

Sleeper (rail):
    Railway Tie

Slip Road:
   On-Ramp, Off-Ramp

Slowcoach:
    Slowpoke
("Hurry up you pathetic slowpoke!")

Spanner:
    Wrench

Speak Back ("Charles, don't speak back to granny, it's rude."):
    Talk Back
("Don't talk back to your father young man!")

Spring Onions:
   Scallions

Squash:
    Raquetball 
(a near equivalent). Squash isn't really known.

Stabilisers (child's bike):
    Training Wheels

Stag Night:
   Bachelor Party

Stanley Knife:
   Box Cutter

Starter:
   Appetizer

Static Caravan:
   Mobile Home

Streaky Bacon:
   Bacon

Stroke (the dog):
    Pet

Study:
   Den

Sub-Contract:
   Outsource

Supply Teacher:
    Substitute Teacher

Surname:
    Last Name

Suspenders:
    Garter Belt

Swede:
    Rutabaga

Sweets:
   Candy

Swimming Costume:
    Swimming Suit, Swimming Trunks, Bathing Suit