What I do is randomly give shit data to them, some of my real friends confirm it who are in on it. Sometimes I just copypaste whatever random shit I had in another tab - then delete it, sometimes Like things I dont like, but not too often. Ive even uploaded my own pictures (nobody actually visible) from years ago with modified Exif data - its for shits and giggles as they say. Accept those weird friends, but not all, send some friend-requests myself. Comments no, no real messages initiated by me, most of the times try responding with other methods. Facebook only in incognito mode on full screen at all times with windows user-agent.

Been doing this for 3-4 years already. Was fun but now I visit it every other month or so.