Possible Clues:

• Four-string guitars, cut
• Certain beach party instruments
• Cousins of mandos
• Small strings, briefly
• Mini guitars
• Some of them come in 'pineapple' and 'soprano' varieties, informally
• Luau bring-alongs
• Luau instruments, familiarly
• "Aloha Oe" insts
• They may have koa wood bodies