Jaden Smith tricked his dad Will into celebrating his birthday in London so he could drink alcohol.

The Men in Black star's son turned 18 on 8 July, and was promoting his upcoming show The Get Down around the same time. While Will, 47, thought it would be a fun family trip if he, wife Jada and daughter Willow joined Jaden in the English capital in the lead-up to his coming of age, little did he know that the teenager had an alternate motive behind his location choice.

"We go to a restaurant, and Jaden was particularly excited, you know? We sit down at the restaurant and he looks at the waiter and he says, 'I'll have a tequila!'" Will recalled to talk show host Jimmy Fallon. "And I said, 'Woah, man, hold up, what you doing?' and he says, 'Drinking age is 18 in England, dad!' (pulls shocked face) I was like, 'You joker!' I was thinking fast, I was thinking fast, I said, 'Oh, but hold on, hold on, it's only noon in Los Angeles and you weren't born 'til 4pm so you're not 18 yet!'"

Will continued to recall some of trips as a child, including when his father drove cross country in a campervan. When host Jimmy shared his desire to go on an RV road trip, he and Will began planning their dream route, joking that they'd drop their wives off along the way and jet out to Mount Rushmore in South Dakota.

With a family of his own, the actor enjoys spending as much time with his children as possible. Quizzed by Jimmy on how his kids are so polite, Will shared secret behind how and Jada raised them. The couple used a technique called the Circle of Safety, in which the youngsters could say anything they want - even swear - rather than keep things from their parents.

Things have changed now though as Willow is getting older, as Will quipped: "As a father, you do not want a circle of safety with a 15-year-old daughter. You do not. I'm like, 'Baby, you need to start lying!'"