This can represent either a half hearted attempt to smile
A faked smile to hide your true emotions
I SMILF'd at that jerk Joe who thinks he's my friend even though I publicly dislike him.
Kid 1: "You think SMILF will let my girlfriend and I spend the night at her apartment tonight since we can't in the dorms?"
Kid 2: "Of course dude, she's fucking awesome!"
A woman with soccer-playing offspring with whom one would like to have sexual intercourse. The SMILF's natural habitat is the suburbs, though they may be found in urban settings as well. SMILF offspring often have last-name first-names (i.e., Madison, Parker, Walker, Taylor, Quinn).
Other common SMILF affiliations include, but are not limited to: Range Rover, Whole Foods, Nelly, things that are manicured (nails, lawns, etc), Rice Krispy treats, Juicy Couture sweatsuits, visors worn non-ironically, waxes, bunko, dry cleaning bills, college degrees, Oprah, Meredith Vierra, elliptical trainers, pets, and patriotic decals.