Casual summer denim attire, colloquially

• Summer clothing portmanteau
• "Dear Men, You Seriously Need To Stop Wearing ___" (denim-related 2014 Buzzfeed article)
• Tightfitting denim attire that Tobias wears at all times on "Arrested Development"
• Summer denim wear, slangily
• Knee-length denim garment, perhaps

Wiktionary Word definitions in Wiktionary
n. (context pluralonly English) jean shorts, a pair of shorts made from denim (especially, mid-thigh or knee-length)