Christina Aguilera says ''sexiness should be effortless''.

The 32-year-old pop star insists she can feel attractive in anything and doesn't need to get dressed up to feel sexy for her man Matthew Rutler.

Speaking to the new US issue of Maxim magazine, she said: ''I'm such a down-to-earth girl, I'm comfortable in just a jersey and boy's underwear. Trying too hard to be sexy is the worst thing you can do. Sexiness should be effortless.''

Christina also revealed the biggest turn off for her in a man is a guy who wants to woo her with a song.

The 'Your Body' singer - who split from her ex-husband, music marketing executive Jordan Bratman, in late 2010 - says nothing makes her feel more uncomfortable than being serenaded.

Christina - who has a five-year-old son, Max, from her marriage to Jordan - explained: ''The quickest way for me to feel weird and run for the hills is if somebody sits down and serenades me with a guitar. It's not my thing.''

The October issue of Maxim magazine is out on September 17.