In Back to the Future ( 1985) Lorraine calls Marty McFly as Calving Klein because of the underwear. In that year CK wasn't famous outside the US, thus they changed it to

NewtCave: Recap: Back to the Future Part 3: Present Perfect

In Back To The Future, why do people keep calling Marty McFly

In Back To The Future, why do people keep calling Marty McFly

In Back To The Future, why do people keep calling Marty McFly 'Calvin'? - Quora

Calvin Klein, Futurepedia

Scene 9: Calvin & Lorraine

Poor Product Placement — Calvin Klein - Back to the Future (1985

Daily Dialogue — February 9, 2018, by Scott Myers

In Back To The Future, why do people keep calling Marty McFly

In Back To The Future, why do people keep calling Marty McFly

Rebecca De Mornay

NewtCave: Recap: Back to the Future Part 3: Present Perfect

NewtCave: Recap: Back to the Future Part 3: Present Perfect