Castro, who was among the male celebrities who participated in the annual event, was seen kneeling in front of the audience when someone suddenly grabbed at his crotch area.
The actor took to his Instagram account to comment on the incident.
"Salamat sa #cosmopolitan at sa lahat na nanood. Dun sa nanghawak bonus na sayo yan! Wag ka na maghuhugas ng kamay," he wrote in the caption.
Castro's girlfriend, Kapamilya actress Sunshine Garcia, was also part of the audience.
In a separate post of her own Instagram account, Garcia praised her boyfriend.
"...ikaw pa din ang #1 at pinaka favorite ko sa lahat...Kita mo sa sobrang hot mo may hindi nakapagpigil hahaha! Congrats hubby..." she said in her caption.
source: www.abs-cbnnews.com