what are some pink decoration ideas for a teenage party?!

Take a tall clear cylindrical glass container and fill it most of the way with pink tinted water...
Now either buy a fancy mask or make your own (fabric? felt? card stock?) because it's going to wrap around the "vase">>cut a rubber band in half and glue gun it to mask so it's snug against the "vase"..
Embellish the mask if making...sequins, jewels, glitter,--punch a hole in top left corner of mask (when you're looking at it) and string curling ribbons through it so that they hang way down in different lengths...can also attach small bells. Attach tall feather plumes behind the hole...and be sure the mask has eyes...because you can now CAREFULLY place a tea light candle in the "vase" and float it and the shimmering glow will come through the mask. (Make sure to use strikingly different shades of pink...perhaps adding a touch of a black contrast in there to make the whole thing stand out--just because your theme is pink, doesn't mean you can't use a neutral, contrasting color for effectiveness).

Make some decorative "place mats":

Cut 2 pieces of wax paper to the size of a place mat.

Take some pink rose petals and put them all around on one sheet--

Get some pink(s) crayon shavings and sprinkle all over (this is what makes the
wax paper stay together. (Don't overdo it)...You could also add a picture writing the year and Name on it.

After you're done, place the other wax sheet over, make any changes.

Use the iron all over the paper and see the crayon melt in with the art work. You are done. (Don't have iron TOO hot).

Make keepsake ornaments to give to guests: Use any shape cookie cutter you like for this project>>
Be sure to make a hole at the top to string a pretty ribbon through. Then when cool, paint them and put each guests' name on one to take home....maybe make the cute "Energizer Pink Bunny" ;0
String them all up on a line across the party area...or tack them up on a cork board so everyone can admire theirs. Can glue on embellishments...just be creative!
http://www.doityourself.com/stry/dough-o…

A florist can create a modern centerpiece that is based on the pink theme.

Go to your town's best party supply store. Most have their napkins, cups, plates and utensils grouped by color.

Couple the flicker of a yellow candle flame with your pink accoutrement by lining the table with votive candles. Holders can be found in pearlescent colors

Glitter

Helium balloons in pink

Gift bags wherein everything inside is pink

Are you doing it in your house? If you do it indoors, our in a party tent outside, you could hang lots of pink paper lanterns in different shades of pink (light pink, dark pink, hot pick) at different lengths.
For example: http://www.lunabazaar.com/paper-lanterns…

Do a centerpiece of different shades of pink flowers (roses, carnations, etc.) in a long rectangular vase so it runs the length of your table. Or, you could do a centerpiece that is vases and jars of different sizes/heights filled with pink candies like bubble gum, flying saucers, jelly beans, etc. Another idea would be to get a cupcake stand and make pink cupcakes with white icing, use the stand/tower filled with cupcakes as your centerpiece.