(US gay) a penis that is substantially larger than expected when erect.
|[||Sisters of the Night 103: She’s a lot of fun and she plays the accordion].|
|Queens’ Vernacular 51: accordion (late ’60s) an unexcited unexciting cock which expands to a much greater length when aroused.|
|Gay Sl. Dict. [Internet] accordion: [late 60s] a penis which becomes dramatically longer in length when aroused.|