How would a meeting of the Reptilian Sexuality Club go down, and what would feuding librarians have to say to each other? The members of Needs Improvment took on these tricky questions, while wearing pajamas, in a witty, spontaneous, and absolutely hilarious performance on Jan. 11 in the Roberts-Dubbs Auditorium. The Needs Improvment troupe was both captivating and memorable.

Actors in most theater performances spend weeks or months memorizing their lines and nailing down every detail of the scene. Improv operates on a different principle. They make it up on the spot, drawing from their own imaginations. In order to keep the performers on their toes, skits are prompted by suggestions from members of the audience. Many of the suggestions are completely off the wall.

For their opening act, the company asked the audience to name a color. This being a sophisticated Brookline crowd, no primary colors were named (except for yellow). Spectators cried out for crimson and periwinkle. The director, Mark Vanderzee, settled for vermilion. Then, the audience was promptly introduced to a character named Vermilion.

Improvisation requires actors to come up with both monologue and dialogue. Needs Improvment performed both admirably. The Reptilian Sexuality Club scene, for example, opened with banter among the imaginary club members. Then it broke into soliloquies, in which each of the members offered heartfelt justification for why they joined, from being attracted to reptiles, to wanting hugs from nerds. Altogether, it was comically unpredictable.

In a brilliantly executed skit involving feuding librarians, played by junior Cait Donahue and senior Nick Sturman, Donahue’s character revealed that she was insecure about her vocabulary after Sturman referenced his hate for the Merriam Webster dictionary. Then the skit was re-performed in less than 20 seconds, and finally it became a frantic muddle of librarian hatred in less than ten.

The thrill of watching improv is tracking unexpected twists. When the audience offered the prompt “sleepover with grandmother Janice,” probably most viewers expected to hear about a story about a grandmother. But the actor instead informed us that “grandmother Janice” was just the name that he had adopted for his mother. It turned out that he had complicated relationships with both his mother and his significant other.

The audience wanted to see Mike Pence “coming out.” Senior Ceci Cipullo gave her clever take of this by having Pence come out — as a Democrat. This merited laughter and applause from everyone in the auditorium

For the final act, the improv group was just as surprised as the audience when  Vanderzee announced that they would draw inspiration from within. Small groups of actors went to the stage with  short improv pieces, none lasting more than 30 seconds, in a blitz of unexpectedly linked themes. In my opinion, this last segment was a perfect ending to a show full of quick thinking and humor.

At its best, improv reminds us of the endless possibilities of the imagination. It’s a celebration of the quickness of wit. In this creative show, the Needs Improvment company succeeded in making the audience laugh out loud with enthusiasm and surprise.