Thick and sticky and pretty darn viscous, like slime, motor oil, or pancake batter. Gooey stuff sticks to your hands, messes up your clothing, and gums up the works in your expensive electronic items. You can wash gooey stuff off your hands, but it's going to be a whole lot harder to get your clothes, your stereo, or your computer clean afterwards.

Also, obnoxiously sweet behavior exhibited by people in love (or just in lust). Too many gooey love poems will give you cooties.

Come to think of it, too much gooey love poetry can also lead to other gooey substances...