noun
dad joke; corny joke; bad pun
A lame pun or corny joke, typically associated with middle-aged men. Often involves wordplay that is considered unfunny or embarrassing by younger people.
父がまたオヤジギャグを言って、家族全員が苦笑いした。
My dad cracked another dad joke, and the whole family gave a wry smile.
彼のオヤジギャグ
His corny joke was so lame that nobody laughed.
駄洒落 is a broader term for any bad pun or wordplay, while オヤジギャグ specifically refers to such jokes told by middle-aged men, carrying a nuance of being outdated or embarrassing.
Compound of 親父 (おやじ, 'dad, middle-aged man') and ギャグ ('gag, joke'). The term became popular in the late 20th century to describe the stereotypical unfunny puns made by older men.