Megan Fox never tips less than $20.

The 'Transformers' actress - who is currently pregnant with her second child with husband Brian Austin Green - always carries cash in her purse and leaves big tips because she has worked in the service industry herself and knows how hard it can be.

She told Us Weekly magazine: ''I always bring cash for tips, and I never give less than $20. I used to work in a smoothie shop, so I know the value of a tip.''

Megan, 27, always keeps other things to hand in her bag, including pens and a book to read.

She added: ''I only use black Sharpies [pens]. I'm very particular about how my handwriting looks. I'm also reading 'The Books of Enoch', which was once part of the Hebrew bible. My favourite TV show is 'Ancient Aliens', and this book describes angels in a way that sounds extraterrestrial.''

Megan previously revealed she is having an easier time with her second pregnancy and it hasn't been as hard as her first pregnancy with 15-month-old son Noah.

She said: ''For the most part, I would say it's been a lot easier. I think that could have a lot to do with the fact that I already have a baby, so I'm so distracted taking care of him, that I don't really have time to sit and lament on the fact that I'm pregnant or indulge my pregnancy.''