A groomsman plied a 15-year-old bridesmaid with alcohol at a wedding then had sex with her.
John Sylvester Young, 29, has been jailed for up to 23 months after admitting statutory sexual assault and corruption of minors in Pittsburgh, Pennysylvania.
A court heard how Young accompanied the victim, who was related to the groom, during the wedding reception in September 2016.
He then bought her alcohol, kissed and touched the girl during the evening.
At 4am the next morning, she came to his hotel room where they had sex, the Tribune-Democrat reports.
Young then continued contact with the girl after the wedding, encouraging her to send a series of nude pictures to him via Snapchat.
The groom eventually found out and confronted Young who admitted the offences.
The girl later told police she had contracted an STD as a result of her encounter with Young.
He must register as a sex offender for life.