What happens if I cross the ADIZ line without a flight plan and no clearance or contact with ATC?
In the late 60's, in a C152. I flew a guy, at a low altitude out of Key West to the Marquessa Islands area to look for sunken Spanish galleons.  On the return trip I was nervous flying at 200 feet above the ocean and climbed up to 3,000 feet.  After a few minutes al said altitude my windscreen flashed black. A F-4 had come from behind and below - zoomed up a few yards in front of me! Looking behind me I saw his wingman, gear and flaps down, S_turning on my six.

A quick call to FSS clarified the situation.

That is what happened to me upon inadvertent entry into the ADIZ. I don't expect it has changed.  There were no followup actions other than the echos of the F-4's pilots laughter.