What’s Eating Him?
Idiom: What it is eating (somebody)?
Something that you ask when somebody is angry and you want to know why.
(somebody) can be replaced with him/her/you or names
From Roel
I got this line from the Ice Age movie that my daughter watched about 1027 times until now. :p
I Get It! 
walah…moga2 soal2 ini gak muncul di tes TOEFL….:p
Karena ini idiom informal mungkin nggak kali, ya? but who knows 😀
maybe in EILTS test?