They sell things specifically made for this purpose.
I like how tempered this response is.
Hitachi magic wand..............they sell it at CVS.
cucumber...ccell phones,, oh Im cuming right now
Look for the Hitachi vibrator, it is powerful as heck. It really is called a Hitachi I am not funning here. If you have a lot of money buy her a Sybian its basically a vibrating saddle, women love it that try it. Then there is the Rabbit available at most any adult store.
Zucchinis, cucumbers, ping pong paddles (and their handles), broom handles, clothes pegs, fish hooks, dog chains (with collar).
Depends on, ahem, the size of things.