Big Time Rush singer Kendall Schmidt is a generous man -- paying off a $243 ticket some random female fan got while speeding to his concert -- but there's no such thing as a free lunch ... and Kendall wants some big things in return.
Sources close to Kendall tell TMZ, a girl emailed the singer this week, claiming she got the speeding ticket in Rochester, NY, while hauling ass to a show for Kendall's side band Heffron Drive.
The girl said she's a broke college student and couldn't afford to pay it ... so she begged Kendall for some financial help.
According to sources, Kendall agreed to pay the ticket on the condition she graduate with a 3.0 GPA minimum. He's also asking her to volunteer 20 hours of her time to benefit her community.
He's not joking either -- we're told Kendall plans to follow up with the girl regularly to keep her honest.
Pretty funny ... most celebs get off with less after REAL crimes.