The Block's Emma and Sam reveal the real reason they wound up sharing a bed

What they thought would be a bit of fun "backfired". Photos / TV3

The Block's Emma and Sam are dealing with some guilt after they were caught in bed together on Wednesday night's episode of the show.

Not because they did anything they regret that night, but because they lied.

The pair have since revealed that it was all a prank, telling Woman's Day "it was a group idea, we were all in on it".

Sam and Emma's prank got a little more out of hand than they bargained for.

But while they say it was all in good fun, Sam says the whole thing "definitely backfired on us" as they weren't prepared for just how far it would go or how much attention it would get.

He says he feels "slightly guilty" now, particularly as he received a lot of messages from fans after the episode aired.

And Emma had to deal with her family and friends who were "quite shocked" because she hadn't given them a heads up.

Nevertheless, both Emma and Sam are adamant there's nothing going on and they are more like brother and sister than anything else - it was just a prank gone wrong.

The Block NZ: Girls vs Boys airs Sunday nights at 7pm and Monday-Wednesday at 7:30pm on TV3.