Sandra Bullock has finally revealed how she kept her adoption of baby Louis a secret for so long ... she has friends who "know how to keep their mouth shut."
In her interview with Matt Lauer, Sandra said there are "good people with integrity" out there who "don't sell out their friends" ... and that her friends know that if they screw up and run their mouths she'll "cut them."
Lindsay Lohan sure could use a couple friends like that.
Sandra Bullock -- My Friends Don't Sell Me Out
8/31/2010 9:30 AM PDT BY TMZ STAFF
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