Trigger a mobile touchscreen with a mobile phones floating ground?

Hi there - this may be a totally stupid idea that highlights my complete ignorance, but having read a previous Arduino article on triggering a touchscreen it would suggest that grounding a plate/penny/contact on a captive touchscreen would mimic a finger press. http://forum.arduino.cc/index.php?topic=157859.0

My question is, do you think this could be achieved by using the floating ground off the mobile phone itself? e.g. if a wire was connected to a penny, and the other to the ground pin of the devices USB socket, would connecting the 2 trigger the screen, or more likely brick my phone :D

Basically I am looking for the simplest way for me to use a joystick trigger to click an area of the screen, and am wondering if would sticking the trigger's in/out contacts between the penny and ground do the job.

Many thanks in advance

Joe.

do you think this could be achieved by using the floating ground off the mobile phone itself?

Why do you think your phone has a "floating ground"? That suggests that you don't understand what ground means.

Again - apologies I'm an electronics idiot - I heard the term floating ground and assumes it was some built in sink some-such to simulate the effects of ground (pause for mocking laughs) - my apologies.

I'm not usually that stupid (honest) just way out of my depth and looking some free help/advice to solve a problem

Thanks anyway

Joe.