Michael Webber, formerly Michael Clark, was a hippie in the late 1960s along with his girlfriend Jennifer Clark. They were traveling to the Woodstock Festival in August 1969 when they picked up SG-1, who had accidentally traveled back in time from the year 1999.
They agreed to take SG-1 to New York City so they could met with Catherine Langford and discover the location of the Stargate. They did not tell Michael or Jenny where they were really from, for fear it would change history. They managed to elicit the cooperation of the two hippies by pretending to be aliens trying to return to their own planet.