Expressions (phrases, clauses, etc.), Noun
marriage due to unintended pregnancy; shotgun wedding
see 出来婚
そこのお店の息子さんが、今度この土地の女の子と出来ちゃった結婚をすることになってる。Well the son of that shop's family, seems it's come about that he's to have a shot-gun wedding with a local girl.
Also written 出来ちゃった結婚【できちゃったけっこん】