The biggest gauge size as far as the measurement of gauges goes is 00g. Some people go to 000g, but after that they go to fractions of inches.

Lobes can be stretched as far as someone may want given lots and lots of time, patience, and care. There's a guy named Bear that has his lobes stretched large enough to rest against his shoulders and then some.

What you need to keep in mind when it comes to stretching is time. People that go from 20g to 0g over the summer are retarded. They think they're cool because they're "hardcore" and can take the pain, but all they're doing is f*cking up their lobes for life. Stretch slow, listen to your body, and be patient.