Ever thought you could make your own Fringe show, but never had the spunk (or, ahem, talent) to make it happen? Baby Wants Candy is here to help. Just yell out the name of the show you've always dreamed of, and they'll make it up and perform it on the spot.

Baby Wants Candy is fully improvised musical comedy, backed by a full band. And it's a different show every night. So it's certainly one of the most unique experiences you're likely to find in the Garden of Unearthly Delights this year.

With previous titles including "Kanye Westside Story" and "Donald Trump goes to Hogwarts", I was treated to the opening and closing performance of "Fifty Shades of School Photographs".

The cast starts performing the first song within seconds of hearing the title. It's bloody impressive to see an ensemble of six singing lyrics that are being invented as they're sung, in at least a semblance of harmony. They must have some serious mind meld going on.

Within the first verse, we have our setting in a 1950s US high school. Characters develop over the next couple of scenes, spilling out of the evolving dialogue. The level of crazy ramps up at a frenetic pace.

The story is vaguely as you'd imagine – a mash up of Fifty Shades and Grease – with some suitably ridiculous moments thrown in for good measure. Christian Grey's origin story is a highlight, with some very awkward illustrative miming involving a human dildo to accompany the song. The ending pulls together OK, as they try to scrounge a moral lesson from the tale.

You really get sucked into the storytelling because neither you nor the cast have any idea what will happen next. The cast are clearly having rollicking good time though, with some friendly competition on who can come up with the funniest segments. The fun onstage is a big part of the joy of this production.

Special props must go to the band, mostly locals recruited for this Fringe run, who roll with the punches and keep the momentum of the show going.

Baby Wants Candy is brilliant. The cast are hilarious, inventive, and craft a contagiously joyous atmosphere. You'll definitely want to see it twice.