MEGA EDIT: Ubisoft fixed this on 2/26/14
Friends should now be the players shown in 4 scores to beat. You can also keep retrying and beating the same friends over and over again. They do NOT have to be one of the scores in the 4 listed. As long as you beat a friend, even if they only made it 1 meter, it will add to your 30 required. This achievement is correctly tracked in the Achievement App and will show your % towards completing it.
If you don't have any friends playing, OR your friends are just too good, you can load a challenge and note the 4 worst times. Send these people FRs on LIVE. They do NOT need to friend you back. Then back out of the challenge and jump back in. The ubisoft servers do NOT recognize new friends until you back out the painting area.