Gerald Koh (许国欢, born 19 September 1984), better known by his stage name Boy Thunder, is a Singaporean radio personality.
In June 2014, he joined rival station 987 and hosted the night show "Itchy Pyjamas" from 8pm to 12 midnight.
Koh attended Catholic Junior College after graduating from St. Gabriel's Secondary School.
In March 2013, Boy Thunder, alongside Adam Piperdy, presented the longest marathon show in Singapore radio history, which lasted for 77 hours and 11 minutes with no breaks in between.
The duo also managed to achieve a Guinness World Record for the Longest Marathon for a Radio Music Show DJ – Team.