Neil Patrick Harris isn't one to turn down an invitation received on Twitter. The How I Met Your Mother star, who is in Toronto filming his new movie, Downsizing, recently said yes to an offer that he attend a play at the city's popular Fringe Festival in his downtime.

His appearance at the production happened as a result of a tweet he shared asking for tips on the city.

One respondent was Kat Sandler, the creator of the play Bright Lights, who asked Neil Patrick to pop by one of the performances.

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“Within 20 minutes he had direct messaged me about coming to the show," she told Toronto Life. "It was totally sold out. We had to Mission: Impossible him into the theatre.”

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What that entailed, according to the report by the publication, was a covert operation that included sneaking the actor in the back door before the show started. As a result, most members of the audience didn't even know he was there.

Neil Patrick was so "lovely" and friendly, he went on to pose for a picture with the play's cast.

Over the weekend, the duo went on to see two other Fringe shows together: True Blue and Romeo and Juliet Chainsaw Massacre.

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It's no secret that the 43-year-old is a theatre fan. He's hosted the Tony Awards four times and won one of the statues for Best Leading Actor in a Musical in 2014 for his role in Hedwig and the Angry Inch.

The father of two can next be seen in the project he's working on in Canada. Downsizing is a sci-fi comedy featuring some of Hollywood's biggest stars, including Matt Damon, Kristen Wiig, Jason Sudeikis and Christoph Waltz. It's set to be released in late 2017.