married over a broomstick

married over the broomstick :
A "broomstick" marriage was an illegal marriage, solemnized, according to the Oxford English Dictionary, by having each party jump over a broomstick. The term, common in the 19th century, has been in use since the 17th (OED, "broomstick").

In the nineteenth century, there was a tradition of besom weddings or jumping the broomstick. Unions were forged when the couple jumped over the broomstick together and dissolved by reversing the process. Some couples performed this ritual prior to their one night stand, but there are many instances of long lasting relationships beginning in this manner.

get married over a broomstick - соединиться невенчаным браком, не жениться законно

see also
гражданский брак
[out of wedlock]