Testing the audio is important—they should listen on different speakers or headphones to see how it sounds. Sometimes a certain phone might muffle some effects, so testing across different devices ensures the prank works as intended.

Wait, the user mentioned "best friend," so maybe they want to keep it within a good-natured prank. Maybe suggest setting up a loop of the distorted audio to play on a friend's device or sending it as a voice note. But again, emphasizing the consent aspect.

Important steps: recording the base audio, applying effects in layers, previewing each step to avoid overdoing it. Maybe suggesting exporting in different formats to see which one sounds the worst. Also, tips on using online tools for quick effects if they're not into using DAWs.

Maybe include a checklist of effects they can mix and match, and some creative ideas like layering multiple distorted tracks on top of each other. Also, maybe adding some reverse audio or random samples from other sources for a chaotic effect.

But I should also mention the responsibility part. Making sure they know not to use this for harassment or in a way that could hurt feelings. Trolling should be consensual and light-hearted. Also, some technical troubleshooting—like making sure the audio isn't too clipped, managing headroom to prevent distortion from being too harsh.

Another thing: if they're using a smartphone, there are apps like Voice Changer, but those might not have as much flexibility as desktop software. So maybe recommend specific apps if they're on the go.