Flirting with other people...

What do you guys feel about flirting whilst in a relationship? my girlfriend and I talked to it, I think after her admitting that she is a huge flirt lol! Anyways, we both said it was ok as long as it wasn't serious flirting and only for fun. Honestly, flirting is sooooo much fun! We're both secure enough in our relationship to be able to trust each other not to cheat or anything. Neither of us thinks flirting is cheating, unless its that kind of flirting where you're seriouly trying to get in their pants.

So what do you guys think? Is flirting cheating? Would you be ok with your girl/guy flirting with someone else? Do you think it matters differently for men than it does with women?