One possible skeptical scenario is Russell’s 5 minute hypothesis. This is from The Analysis of Mind…

In investigating memory-beliefs, there are certain points which must be borne in mind. In the first place, everything constituting a memory-belief is happening now, not in that past time to which the belief is said to refer. It is not logically necessary to the existence of a memory-belief that the event remembered should have occurred, or even that the past should have existed at all. There is no logical impossibility in the hypothesis that the world sprang into being five minutes ago, exactly as it then was, with a population that “remembered” a wholly unreal past. There is no logically necessary connection between events at different times; therefore nothing that is happening now or will happen in the future can disprove the hypothesis that the world began five minutes ago. Hence the occurrences which are CALLED knowledge of the past are logically independent of the past; they are wholly analysable into present contents, which might, theoretically, be just what they are even if no past had existed.

I am not suggesting that the non-existence of the past should be entertained as a serious hypothesis. Like all sceptical hypotheses, it is logically tenable, but uninteresting. All that I am doing is to use its logical tenability as a help in the analysis of what occurs when we remember.

Today’s New York Times has a story claiming that there are certain hypotheses that cosmologists take seriously that other cosmologists say predict that the Russell scenario is highly probable.

(They don’t call it the Russell hypothesis, but that’s what they’re talking about).

UPDATE: I should be more careful. It’s not that what some cosmologists say predict Russell’s skeptical scenario…The scenario that Russell imagines is that the universe was created 5 minutes ago. The cosmologists in question endorse the multiple universe hypothesis – this is incompatible with Russell’s scenario…so it can’t confirm it.

What some cosmologists think it does confirm, however, is the hypothesis that it is highly probably that you are just a momentary flash of organized matter created just moments ago that is complex enough to have thoughts and apparent memories of having been around for a long time.