We were at my in-laws for Father's Day and my husband accidentally told our baby's name! My SIL heard it loud and clear so she knows now. She lives with MIL and FIL so I hope she can keep a secret but I really doubt it. The only good part is that he feels so bad he might let me have the middle name I have been campaigning for. But I only want to use it if he likes it. So far neither of us has come up with a better name though.
The kind of funny part is that our kids have known the name for a long time and managed not to tell the in-laws. My oldest did tell some people at school. I guess maybe we will be breaking tradition with this one.