Check the calendar for "bring a friend free" they do that often
They have a few. I'm a Gold membership and this is what I get: Bring a friend 50% off. Or Present your valid 2018 Six Flags season pass and an O'Reilly coupon at the front gate of a participating Six Flags theme park and receive 50% off one general admission ticket 5/28/18 - 9/03/18. Visit a participating O'Reilly store and grab your O'Reilly coupon for details. $25 for a friend to Hurricane Harbor.
Depending on the season pass, you might be able to bring a friend for $25, however I would recommend you call, just to confirmed.
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