What is a really really good practical joke to play on someone for April fools day?

I mean REALLY GOOD.

Answers:
If you've just started dating someone ,and they don't know you too well, tell them you suddenly got married to an old flame. Top if off with a visit to them with your husband/wife {accomplice}, complete with ring, pictures, and everything. Tell them it's something that just happened, and you just had to share your "joy" with them.

Other answers:
to make fun of them and make them pee in their pants.

to make fun of them and make them pee in their pants.
annoy them i guess
Plastic wrap under the toilet seat. When they sit to pee, it will bounce off and hit them in the butt.
you like them. huge crush

but then after the day is over. say you were kidding
go to thier house and tell them you must stay there and annoy them for hours because you stay stay home,they ask why and you replay,"cause my house was stolen."
O.o
I don't know if we live in the right political climate for this, or if you live in a small enough town, but I always thought a obviously fake arrest and an hour getting interrogated for something mundane would be kinda funny.
put a ketchup pack folded in half under the toilet seat
unscrew the cap off the salt shaker so when they go to use it salt gets all over them?
Get their spare key to their car and when they go somewhere, move it! hah hah hah!
LETS SEE REALLY GOOD? TAKE A PIECE OF PAPER AND RIGHT BIG BUTT ON IT AND PUT IT UP SIDE DOWN WITH TAPE ON IT! SO RIGHT BEFORE SOME SITS DOWN PUT IT RIGHT UNDER THEIR BUTT! SO WHEN THEY STAND UP THEY HAVE A SIGN ON THEIR BUTT THAT SAYS BIG BUTT! HA HA HA HA HA! LOL! VERY PRATICAL!


FRUM-DURR
wear a clown's costume and act very serious..
asked them out. then don't show up.
tell them that they have a rip in the back seat of there pants and you can see what color under waere they are wearing
tell someone that u got a deadly disease and that u going to die in seven days.
ask ur bf to break up. do not say anything just say that.
Tell them your pregnant!
Put baby powder in there car vents and set the fan to high so it flys out over them when they start the car.
have a can of silly string hidden and make it look like you are going to throw up then just when it looks like you can't hold it in any longer bring the can up hidden aim and shoot, scares the crap out of them.Just try to do it quick so they don't see the can.
When there are people put a whoopee cushion with some fake dog poo on his/her chair.
CUT YOUR HAND OFF AND BLEED ALL OVER THEM
phone and tell them that they have won 1000 bucks
If it is to prank a married woman this works well.
First call her home and pretend your an employee of the front desk of some hotel.
You: Hello I'm (fake name) and I am calling from (insert hotel). It seems you and your husband left some personal possessions in your room yeaterday.
After she denies being in any hotel. you ask..
You:"Isn't your husband (His Name and some info)
Her: Yes
You: "And aren't you (her name) a tall blued eyed blonde"

More Questions & Answers...