gate crasher

Translations
незваный гость
He was a gate crasher at the wedding.
Он был незваным гостем на свадьбе.
Definitions
A gate crasher is a person who attends an event, such as a party or concert, without an invitation or ticket, often sneaking in or bypassing security measures.
Words
gate

noun
ворота
crasher

noun
непрошеный гость