Disclaimer: Everything you know belongs to the genius that is J.K.Rowling.

Soon the new-found friends chirpy young-girls chatter was suddenly interrupted by bangs on the door. Trough the frosted glass a couple of messy heads was visible.
"That's bound to be James and Sirius." Lisbeth grinned, and turned to the four girls who had confessed to pelt the two boys with dungbombs. Dani grinned evilly and, with a flick of her wand, undid the locking spell on the door, causing two dark haired boys to topple into the compartment. They hurriedly got to their feet.
"Ah-ha!" one of them screamed, pointing an accusing finger at Drew, who had fallen onto the floor along with Erika in hysteric laughter. The rest of the girls where up to their elbows trying to keep their laughter under control. At last Lily rose and pulled out her wand, turning it to the two boys. Helen held her back with a hand on the arm.
"Thought you said you were muggle-born?" Lily nodded in agreement.
"But, we haven't learned any magic yet!" Lily shook her hand off.
"I've looked trough our books, I think I can manage this." She pointed her wand towards the two boys and flicked out a cleaning spell and a smell-removing charm over them.
"That should do it." She smiled, and sank back into her seat. The two boys stood as if petrified. One pulled at the others sleeve.
"We don't smell anymore James, do really think we should pelt them with Jelly Balloons anyway?" The other seemed to consider this for a moment, but let his hands, till now concealed behind his back, drop, revealing several small balloons filled with itching magical jelly. Lily felt a sudden relief, and was glad she had taken pity upon the boys. They grinned sheepishly in apology and retreated, letting the compartment door bang shut. The girls breathed a sigh of relief.
"If we keep having you on our team," Dani said, "We might just escape with more than our share of mischief!"