Tell Deidara he's a she then pull off his pants to prove your point.
Do this in front of entire Akatsuki.
Write a M rated Deidara Sasori one-shot and give it to him claiming you found it in Sasori's room.
Watch how he reacts.
Take the fic and show it to all of Akatsuki, now say Deidara and Sasori wrote it about their late night adventures.
Replace every article of clothing he has with womans clothes (do this while he's in the shower).
While his back is turned cut off a lock of his hair.
Make a shrine to him and wear the piece of hair as a necklace.
Make sure he walks in on you worshiping him in the creepiest way you can think of.
Stalk him where ever he goes.
Chain him to a bed and tell him you will love him.
Tell him that you love him so much after your done you will kill him with you so you can make art together.
Knock him out, drag him outside and wake him up, when he freaks out, suggest sweetly that he had a nightmare.
Hide all of his clay in Sasori's pants, see how far he'll go to get it back.
Record him singing in the shower and post it on youtube.
Hide under his bed while he's going to sleep and repeatedly rasp, "Red Rum".
Squeeze super glue on his hair brush before he wakes up.
Rip out the hair brush half way through the day.
Kick him between the legs and say, "Now Sasori can be the daddy and you can be the mommy!"
Pretend you're talking to him then go over to Sasori and give him a kiss. Say it's from Deidara.
And lastly, run like a bat out of hell.