Carrie Ann Inaba Makes Bizarre Incest Comment on 'Dancing with the Stars'

Carrie Ann Inaba might have the steps down in the ballroom ... but she made a serious misstep while complimenting a pair of dancers -- heaping incestuous praise on them.

Here's the deal ... Paralympian Ezra Frech and his pro partner Daniella Karagach danced a steamy Argentine Tango Tuesday night that got the whole ballroom hot -- and probably put the pair in an awkward position, since their relationship has regularly been described by both as big sis/lil bro.

Carrie Ann knows that ... and, inexplicably in her excitement, decided to mention it -- by saying, "The intimacy. Turning your sister into your lover for one night is all good!”

We're not sure getting hot and sweaty with a sister off the dance floor is cool ... and neither was Carrie Ann's fellow judge -- and former pro -- Derek Hough, who said, "That was weird."

The internet thought so, too ... there's a whole lotta jokes online roasting Carrie Ann for this line, as you might imagine.