An illusion yoga pants created causing a flat booty-ed person's back side to appear more curvy and voluptuous than it would in normal attire.

note: lululemon is an athletic brand that specializes in yoga pants
Chet: Dayum I didn't realize Sara had such an ass on her!
Chad: Nah man! It's a lululemon-illusion! That girl's ass is flatter than a pancake.
by Just Curly September 3, 2016
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