He does that all the time- Says he's going someplace and will pay for anyone who wants to join him. He was in Hollywood for Dancing with the Stars and was routinely buying 100 tickets to whatever movie was playing, free to the first 100 people who showed up.
After last season's playoff loss, he sponsored a "Tour for Giving" where he paid for 9 people to go on a luxury tour bus and travel from city to city doing charity work until they reached Miami for the pro-bowl. At the end of the trip, he took all 9 of those people to Disney World and paid for their flight home.
Yeah, he clowns around a lot, but stories like that make it easy to get over his antics on the field.