The dark-haired hunk revealed the news in an interview with 'Dory' actress Ellen DeGeneres on her chat show 'The Ellen DeGeneres Show', where he said: "Wow. A car trunk. The trunk of a car. Enclosed."
However, the comedic host was sceptical about the 'Pirates of the Caribbean' star's replies to her probing questions.
She said: "You're not being honest. I would ask you more but you won't answer them honestly. You're no good at this game."
Although the 59-year-old presenter doubted Johnny's responses, she continued to grill him about his private life.
She asked: "Who was your first celebrity crush?"
And the tattooed-hunk revealed 96-year-old actress Carol Channing stole his heart at a young age.
He replied: "Carol Channing."
But the star - who had a high profile split from his previous partner Amber Heard last year after 15 months of marriage -has admitted the best person he has ever kissed is his 'Pirates of the Caribbean: Dead Men Tell No Tales' co-star Javier Bardem, and Penelope Cruz.
He quipped: "Javier Bardem. And Penelope Cruz."
Meanwhile, Johnny has revealed his favourite body part is the back of his head, and he is filled with a "little tinge of excitement" when he catches a glimpse of the area.
When asked about the preferred area of his body, he joked: "Back there [back of the head] for the moment. I might get a little tinge of excitement. My shoes are my favourite part of my body. I have had them surgically put on."
But the star isn't a big fan of his bottom, and he has admitted he doesn't necessarily "like" his derriere but "accepts" the area.
He said: "Like it? I accept it."