UPDATE: CBS announced Wednesday (Aug. 17) that Friday's special episode is going to feature the Ziggy Marley concert. However, the press release reads, "Houseguests will have the opportunity to compete for prizes, perks and power, and seven-time Grammy-winning reggae artist Ziggy Marley stops by to surprise the houseguests with a performance."

This doesn't mean that we're wrong about Friday being a battle back competition for the jurors, as the players are not only competing for prizes but "perks and power." We shall see.

UPDATE II: There WILL be a jury Battle Back competition, but it is NOT airing Friday. It is happening next week after there are five jury members.

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There's a special "Big Brother 18" episode airing this Friday (Aug. 19) and Zap2it is 99 percent sure we know what's going to happen during the broadcast. Read on for our theory -- but be warned, some live feed spoilers are ahead.

OK, so there is a possibility that the special episode could be a clip show or something, but we don't think so. It seems fairly obvious that Friday's episode is going to be a battle back between the jury members and here's why.

The round-trip ticket twist is over

The round-trip ticket was introduced the week Frank was evicted and lasts through five evictions. So Frank, Da'Vonne, Zakiyah, Bridgette and whoever leaves on Thursday, Aug. 18 will account for all the possible round-trip ticket holders. Now, even though we don't know who has the ticket in his or her envelope, production definitely knows because the envelopes were numbered. So chances are that neither Paulie nor Corey (the two nominees) have the round-trip ticket.

Sure, the Friday episode was announced before production knew Victor's nominees, or even that Victor would be HOH. But that doesn't mean they didn't feel fairly confident the round-trip ticket would go unused and hedged their bets. They could always have aired a clip show on Friday if Thursday's evictee ended up having the round-trip ticket.

RELATED: 'BB 18's' Paulie throws quite the tantrum now that he's not in power

You might be thinking, "But no round-trip ticket actually puts 'Big Brother 18' on track to have three people left on Sept. 15, the Thursday before the Sept. 21 finale." And you'd be right. The 3rd-place finisher is always evicted during the first half of the live finale, so that works out.

But this is "Big Brother" and they both A) hate to have a twist wasted, and B) like to keep throwing in more twists.

The last Friday ep was the Battle Back

The special Friday, July 22 episode was the Battle Back competition episode, where the first five evicted houseguests faced off head-to-head for a chance to return to the house. It was an exciting episode and the number of viewers who tuned in was right in line with "Big Brother 18's" ratings, so it didn't take a hit by airing on a Friday night. What does CBS have to lose by airing another one?

This means another double eviction

Double eviction episodes are gold, everyone loves them. So if a jury member gets to return to the house, that puts the numbers off (as we previously mentioned), which means there will have to be another double eviction at some point. Yay!

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Also, you know a second double eviction had to already be planned because a round-trip ticket reveal would have made one necessary.

We kind of already know someone is returning

When Zap2it spoke with executive producer Allison Grodner at the CBS event during the 2016 summer TCA press tour, we expressed our dismay over Da'Vonne being evicted because she's a fun player. Grodner told us, "You never know what could happen. We’ve had a lot of opportunities, remember the round-trip ticket? There still might be … who knows what could happen?"

At the time she made the comments, there were still three people left to reveal their envelopes and Grodner had no idea who two of those three might be, so she couldn't count the round-trip ticket out just yet. But you know production was already planning for the event in which the ticket was not used.

RELATED: 'BB 18' power rankings week 8: The worm has turned

Finally, Grodner also called Da'Vonne "our star," so production would probably be thrilled to have her back. Additionally, it's looking like Paulie is on his way out this week and he's another big character like Da'Vonne. Zakiyah and Bridgette aren't all that exciting -- though Bridgette really came on strong at the end of her run -- but a 50/50 shot at getting a big player back is pretty good for production, especially if they pick a competition that favors the people they'd like to see return.

All in all, if Friday's episode turns out to be something other than a competition for the jury members to return, we will be fairly surprised.