Ratings for Two and a Half Men have been slipping lately ... so maybe star Ashton Kutcher thought kissing co-star Jon Cryer will help!

Kutcher, 33, is still dodging questions regarding someone else he hooked up with -- his rumored affair with 23-year-old Sara Leal -- however his character Walden Schmidt doesn't seem to be affected by any drama whatsoever.

In the clip above from Monday night's episode, after the two actors lock lips, Cryer says, "We're here, we're queer -- get used to it!" Gotta love comedy!