Sonic Grenade is an app aimed for crowd control and playing pranks on friends.
Disclaimer: Read the instructions before using.
Connect the phone to a stereo and turn up the volume. The app generates a very high-frequency sound that is really annoying and headache producing.
You can use the application standalone. Hide the phone somewhere and play a prank on someone.
Sonic Grenade 1.0.4 Nokia S60v5/Symbian^3/Anna/Belle
Nokia Symbian^3 (S^3)
Nokia N8, C6-01, C7-00, E7-00, E6, X7, 500, 603, 700, 701, 808
Symbian S60v5 (S^1)
Nokia 5228, 5230, 5233, 5235, 5250, 5530 XpressMusic, 5800 XpressMusic, C5-03, C6-00, N97, N97 mini, X6, Samsung i8910 Omnia HD, Sony Ericsson Satio, Sony Ericsson Vivaz