Jacob Kulke, 24, reportedly jumped over a fence in an apparent attempt to enter the singer's home. He was nabbed by security, who called the cops on Kulke.
When questioned by police, Kulke said he was Swift's boyfriend and that he had taken a bus from Wisconsin to visit her on her birthday. Police promptly arrested Kulke, who reportedly had a knife with him, and is now being held on $10,000 bail.
TMZ reports that Kulke's previous run-ins with the law include charges of battery, drug possession and disorderly conduct.
Swift, who is currently in Europe with her boyfriend, Harry Styles, turned 23 on Thursday.