The X Factor judge said that she and the One Direction star like to put on fake accents and shout at each other while hanging out in public.
Speaking about their recent day out at this year's V Festival, she told We Love Pop: "We had such a good time. We were dressed in our hoodies and sunglasses, walking around the crowd.
"And because we're both blonde and the same height we pretended to be brother and sister.
"The second people walk past and say, 'Is that...?' we'd start being really loud, shouting at each other in northern accents like, 'What have you done with me ciggies?' or 'Pass us that bloody pint, if our mother was here now she'd blooming kill us! Aahh, come on Chez!'"
She continued: "Tom and Chez are our nicknames when we get together and people look at us like, 'Oh no, that can't be them...' because we're talking in these really loud northern accents.
"Now I've given it away! We'll have to change it. Now we'll pretend to be from Liverpool."
Tulisa also revealed that she is hoping to find a husband and start a family in the near future.