Jack Antonoff found himself in a humorous situation when a fan asked him to sign a poster referencing Taylor Swift’s ex-boyfriend, Joe Alwyn, under the alias William Bowery. The incident took place during a signing event at Rough Trade Berlin on August 31, where a fan presented Antonoff with a poster inspired by Swift’s “22” shirt from her Eras Tour, with the text “Who’s William Bowery anyway?” written on it.

Antonoff, 40, responded to the fan with a shrug and a laugh, as captured in a video shared by the fan on X. The fan later shared a photo of the autograph Antonoff gave her, which included the word “folklore.” This lighthearted moment added to the fun atmosphere of the event.

The Grammy winner was in Berlin for a Bleachers show the day before the signing event. During the concert, a fan in the audience also held up a similar William Bowery sign, prompting Antonoff to laugh once again in response, as reported in a Reddit post.

As fans of Taylor Swift are aware, William Bowery was the pseudonym used by Joe Alwyn, 33, when he collaborated with Swift on several tracks from her albums Folklore, Evermore, and Midnights. While speculation about Bowery’s true identity had been circulating among fans, Swift officially confirmed Alwyn’s involvement in November 2020 during her Disney+ documentary Folklore: The Long Pond Studio Sessions.

In the documentary, Swift shared how Alwyn contributed to the songwriting process, particularly on the track “Exile” from Folklore. She described how Alwyn played a key role in creating the piano part for the song, showcasing his talent and creativity in their collaborative work.

Alwyn’s contributions to Folklore earned him a Grammy in 2021 when Swift won Album of the Year for the record. The album was coproduced by Antonoff and Aaron Dessner of The National, making it a collaborative effort among talented artists.

Despite his success in songwriting, Alwyn expressed that he does not have plans to pursue music composition further. In an interview with Elle magazine in April 2021, he mentioned that it is not a part of his future plans.

Swift and Alwyn ended their six-year relationship in April 2023. Following their breakup, Swift had a brief romance with Matty Healy from The 1975 before moving on to a relationship with Travis Kelce, a tight end for the Kansas City Chiefs. Alwyn, on the other hand, sparked dating rumors with Emma Laird, his co-star in The Brutalist, in March.

Overall, the incident at the signing event in Berlin provided a light-hearted moment for Antonoff and fans, showcasing the fun and playful interactions that can occur between artists and their supporters.