Measure out the blue raspberry syrup and pour it into the blender.
Add the crushed ice to the blender, filling it nearly to the top.
Squeeze in the lemon juice for a subtle tartness that balances the sweetness.
Secure the lid on the blender and pulse a few times to start breaking up the ice.
Blend on high until the mixture is smooth, icy, and has a slushy consistency, about 30-45 seconds.
Pour the vibrant blue slushie into glasses, stopping when the liquid reaches the rim.
Garnish with a slice of lemon or fresh berries if desired for a colorful finishing touch.
Serve immediately with a straw and enjoy its icy, tangy refreshment.