I sometimes get that, if I was looking something up on a shopping site earlier in the day, from that same computer. It's almost always the thing that I was looking up for someone else, or the thing that I bought the week before. There's rarely something that seems particularly thoughtfully targeted.

Then again, I have a policy of not "liking" any kind of brand, group, or anything, don't post links to outside sites, and I randomly mark ads as offensive.