Possible Clues:

• Skull-and-crossbones fraternity, for short
• First national fraternity to officially welcome transgender members (2014), informally
• Largest frat in the U.S
• College frat with the greatest number of chapter houses (200+)
• First college frat to charter a chapter in all 50 states
• Popular fraternity, familiarly
• Member of a popular college frat
• Coll. fraternity with a skull-and-crossbones symbol
• Largest college fraternity in the U.S., in brief