If it's the application I'm thinking of- you answer random questions about random friends and then the friend the question was about gets a post on thier wall.
Hope that makes sense....
So she wouldn't have had to look at his profile to see it. But her DS would have to be friends with the boy.

Dianne- I agree with the others in that you need to block him from yours and DS's accounts though

ETA- guess it's not the one I thought then...