eyebrow-raiser
/ˈʌɪbraʊˌreɪzə/noun
1A person who expresses surprise, scepticism, or disapproval, especially habitually or frequently. Compare to raise one's eyebrows.
2Something surprising, shocking, or noteworthy. Compare to raise eyebrows.
Origin
Early 20th century. From eyebrow + raiser. Compare earlier to raise one's eyebrow(s) (or an eyebrow), eyebrow-raising.