How to Annoy Arya
Sing the Wedding March anytime she talks to Eragon.
Make a show of repeatedly creeping up behind her with a pair of scissors, and try to cut her hair off.
Ask her if she's a lesbian.
Ask her to practise swordfighting with you, then stand stock-still when she wants to begin.
Whenever she says something, grab a megaphone and shout in a very loud, deep voice "THE PRINCESS HAS SPOKEN."
Ask her to learn the Soulja Boy dance with you. When she refuses, run away crying.
Hide a strap-on in her tent, and make sure it is in full view of any visitors.
Paint her stuff neon.
Dye her hair ginger when she's asleep.
When she says something, repeat it in an unemotional robot voice.
Enquire as to her sexual health.
Tell her Eragon had a wet dream about her.
How to Annoy Eragon
Tell him to make his fucking mind up about what species he is.
Claim you stabbed Saphira to death when she's hunting, and watch him shit himself and look for her.
Keep him on his toes by firing arrows at him unexpectedly.
Pull his tent down when he's washing, revealing his underparts to the whole Varden.
Spread rumours that he and Nasuada were caught doing something very improper in her command tent.
Scream "AAAARRRRRGGGGGHHHHHH!!!!! GALBATORIX IS HERE!!!!" and when he comes running out, tell him it's OK, it was just a bird.
Sing "Discovery Channel" whenever Arya is nearby.
Tell Roran that Eragon shagged Katrina, and watch Roran chase Eragon around the Varden camp. Then, when Eragon is sufficiently bruised, tell Roran it was a joke. And that it was Eragon's idea, and he was counting on being faster than Roran.
Ask if he's gay.
Ask if he wants Saphira. In that way.