The brand describes the flavor as the sweet and tart of blue raspberry with a sour swirl (sour apple flavor most likely). You can also get it without the sour swirl as the plain old "Blue Raspberry Freeze."
Both versions are available for a limited time at participating Taco Bell restaurants nationwide. As with the rest of the Freeze line, the suggested price starts at $2.49 for a regular size and you can get it for $1 during Happier Hour (2 to 5 PM).
The current Taco Bell Freeze menu also includes the Mountain Dew Baja Blast Freeze and the Strawberry Skittles Freeze.
Photo via Taco Bell.