What is groundhopping?

"The main purpose of groundhopping is to attend matches in as many different stadiums as possible. Groundhopping is popular mainly in football. Groundhopping probably found its origin in football in the 70’s in England. The term groundhopping is derived from grass hopping. A groundhopper hops from stadium to stadium attending matches. There is a ranking system for the visited grounds but this is not formalized. A universal set of rules for counting ‘hopped grounds’ is not available. A basic rule, however, is that a groundhopper must have seen a match in a stadium to add this stadium to his list. Nevertheless, many groundhoppers like to visit stadiums without attending a match as well. Eventually, every groundhopper counts his own tally and the only thing that matters is the joy that one experiences when visiting grounds or matches." (from Wikipedia)