Does anyone know a REALLY mean prank?

my best friend (mimi) called me the other day and she called me cryin and said "dude, there's someone home" i said "r u alone???" then i heard this really loud noise and she yelled and the call ended, so i was REALLY worried cuz she's my best friend, so i call another friend of mine (daisy) (lives really close to her, thats why i called her) and told her what happened, so in the middle of our conversation i have a call of mimi and said dude, it was kidin, so then i got really pissed @ her, so i want revenge! p.s: and by mean i mean REALLY REALLY mean, thanks