The Appalachian Trail is 2,185 miles long, as of 2013. We had officially walked 1,092.5 miles as of 6/19/13, and we had to airband to celebrate on the halfway mark.
We were in our 7th state (Pennsylvania) and have 7 more to go.
We are aware that other AT hikers have done similar things to celebrate this milestone, and we throw rock n' roll fists in the air with our hiking brethren.
Air Guitar (and Tommy)- Grim
Air Bass (and Gina)- Clever Girl
Air Drums- Dumptruck
Air ?????- Whistle