Zac Efron refuses to eat tuna sandwiches before kissing scenes.

The 24-year-old actor locks lips with Taylor Schilling in new movie 'The Lucky One', and admits he learned the hard way not to indulge in smelly foods beforehand.

He said: ''I chewed more gum that day than typical. No onions! I had a kissing scene one time [on a different movie] and I ate a tuna sandwich and it was the first [scene] I had to do and I got called out on it.

''It was so embarrassing ... You don't do that, don't be that guy!''

When it comes to stripping off for racy scenes, Zac - who previously dated his 'High School Musical' co-star Vanessa Hudgens - uses humour to get past the awkwardness.

He told Access Hollywood: ''You can't take it too seriously ... I think the best way to do it is laugh all the way through it because it's hilarious.''

Now believed to be seeing 'Mirror Mirror' actress Lily Collins, the hunky actor was also linked to his 'The Lorax' co-star Taylor Swift in February - although both were quick to deny any rumours of romance.

Appearing on 'The Ellen Degeneres Show', Taylor said: ''We are not a couple.

''He's awesome, we are not a couple though. You hear people get together when they're shooting movies, co-stars. But not like animated co-stars. You know what I'm saying.''