Believe me, a contented, nursing little one is MUCH less attention-getting than a squalling, hungry baby. It's by far the easiest way to get them to fall asleep.
In a restaurant, sit in a booth in the corner. Wear a modest nursing dress or top. Practice in front of a mirror at home. Get the technique. "Without being noticed" is the key.
not a knock on the practice, just on the people bitching. They appear to be a little overfed..