Setup event:
>On click/touch
• • • • >Set SomeTimingVariable to 1
• • • • >Wait 0.25 seconds (or however long you want the "rapid succession" window to be)
• • • • >Set SomeTimingVariable to 0
Base event:
>On click/touch
• • • • >If SomeTimingVariable is 0
• • • • • • • • >[Do whatever initial thing you want to happen]
• • • • >Else
• • • • • • • • >Set Ball.Speed to Ball.Speed+100 (or whatever speed amount you'd wish to add)
Good luck, hope this helps!