Jimmy Kimmel steps in as guest host of ABC's The Bachelor on Monday's episode, and ET went behind the scenes.

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"Sometimes you wonder if these things are prepared in advance, and I'm here to tell you he at least had no idea what was going to happen," Kimmel told ET.

Kimmel took Bachelor Chris Soules by surprise when he woke him up in the morning.

"He's like, 'I'm a big fan of the show. I watch every episode. I'm here to help you,'" Soules recalled. "I'm thinking, 'What the hell is going on?'"

The timing of Kimmel's Bachelor takeover may be kismet, as the long-running reality dating show faced a 23 percent ratings drop this week. And fans are eager to see Kimmel corner Soules' latest date Kaitlyn. The Canadian dance instructor has raised eyebrows with crass phrases like, "You can plow the f**k out of my field any day."

"Have you ever made out with a woman?" Kimmel asked Kaitlyn.

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"No, Dad, I have not," said Kaitlyn directing her answer towards her father presumably watching at home.

Watch the video to see Kimmel crash Soules' hot tub makeout session. The Bachelorairs Monday at 8 p.m. ET/PT on ABC.