Here are the details from their website:
NATIONAL PRETZEL DAY. YES, IT EXISTS.
Pretzelmaker®/Pretzel Time® will once again host a day-long National Pretzel Day celebration on April 26 at participating stores across the country. This year the company is putting a new "twist" on the holiday by asking customers to "Sing for Your Snack."
To mark this festive day, customers are encouraged to visit their local Pretzelmaker on National Pretzel Day, sing a snippet from a song of their choice and receive a FREE pretzel(with or without salt). Patrons who prefer not to sing won't go hungry - they can simply mention "National Pretzel Day" and receive their free snack*.