Ali Lohan showed off her pencil-thin figure in Hawaii Friday.
The 17-year-old model is on the island of Oahu with big sis Lindsay, and was spotted in super-short cut-off jeans and a midriff-baring tank top.
As RadarOnline.com previously reported, Lindsay was invited to attend the Pipeline Masters surfing competition where her friend Any Irons was being honored. Irons was a legendary pro surfer who died of a drug overdose last year.
After watching some of the competition, the Lohan girls walked to a nearby convenience store for refreshments, but not before Ali playfully sent a karate-like kick in the direction of a friend.
Earlier in the week, Ali attended a casting call in Beverly Hills where Us magazine described her as "alarmingly gaunt and pale -- with noticeably stick-thin arms and legs."
Ali, who towers over Lindsay, turns 18 December 22. She so far hasn't commented on Lindsay's Playboy pictorial which was leaked on the Internet on Friday.