[Jemaclus]

The obvious reason is that your friends are searching for things. When you talk to your friends and your friend mentions that he's going through a divorce, the odds are great that he's looked up a divorce lawyer online, because you're friends, FB figures you'd be interested in the same thing and starts serving you ads for divorce attorneys.

Or if your friend is renovating his house and does a search for new cabinets, you'll see cabinets show up in your ads. And you won't think anything about it until you talk to your friend about his renovations. Then you get home, and your FB is full of renovation ads.

Never attribute to malice or competence (voice fingerprinting for ad targeting )what can adequately be explained by a stupid algorithm ("my friends and I must like the same things" ad targeting).

[shostack]

OP updated this to specify that they saw cockroaches and immediately after saw the ads without searching at all.

The coincidence is certainly odd, but not entirely out of the realm of possibility, especially if this isn't the first time they've had cockroaches (ie. they might be in a demographic/audience segment likely to have these issues and be frequently targeted).

I would also add that FBX partners can leverage a massive amount of 3rd party data, such as search retargeting vendors that can serve ads as quickly as seconds after you've searched for something on one of the data sources they partner with (engines, toolbars, etc.).

[simonster]

Alternatively other people in the same building could have had roaches and somehow made FB aware of it (e.g. status updates), and FB could have targeted him based on his address.