A hoax telling voters what to do while in the voting booth is spreading on Facebook; the best thing you can do is ignore it and whatever you do, don't pass it on.

The post that's being shared says for those voters who are Democrats to "not select the button 'all Democrats' first, because Barack Obama will be excluded from the vote. However, if we choose 'Barack Obama' first, and then 'all Democrats' he will earn our votes!!!"

The trouble is, this is the opposite of what voters should be doing, at least in certain very specific cases.

In some states, "choosing the party first on a voting machine can lead to all of the candidates of your preferred political party being chosen — including the presidential candiate," wrote Graham Cluley, senior technology consultant for Sophos Security, on the company's Naked Security blog.

"That could mean if you get confused and subsequently make a presidential selection for a second time, you could uncheck your vote for the president."

A "typical" message Facebook users might see is this one, said Cluley:

If you see this on Facebook, ignore it, and don't pass it on. Sophos

Despite the stress-inducing all-caps warning — "PLEASE PAY CAREFUL ATTENTION TO THIS!" — voters should in fact pay no attention at all.

Facebook, contacted by NBC News, declined to comment on the ruse.

It's likely to be only one of many digital attempts to confuse voters on Tuesday, so keep an extra wary eye on any emails or text messages you receive, as well as on the social media sites, like Facebook, that you visit. And when you're in the voting booth itself, take your time, follow the instructions, and double-check your choices as you go.

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