Not proud of it, but I lied a lot when I had problems as a teenager. I didn't want anybody helping me. :) The lies came out a bit later, but I had already dealt with the problems, so everything was okay. I don't recommend this in serious cases, though.
If the lie would make them feel happy... Example, my bf lied to my best friend saying that he ate breakfast, tho he didn't.. He did it because he wanted her to continue eating. The three of us are really bad about it. He doesn't eat much, I don't, but the friend he lied to actually eats pretty well xD.
We've all done it from time to time. Those people who tell you they've never lied are definitely lying.
But did I ever think it was justified? Oh yeah.
Back about 1950 I had a schoolteacher named Furness who called all the kids who hadn't done their homework to the front of the room and asked why not. After listening to all the bulldust they were offering I just said, "No excuse." He let them off and caned me. I never again told him the truth about ANYTHING.