(idiomatic) By coincidence, incidentally

Worrying is not necessary, since it is common to make this mistake or for this to occur.

plural of happener

(dated, 1960s-1970s) One who participates in a happening. / A person who makes things happen. / A person to whom things happen.

to find by chance

(obsolete or dialect) maybe, perhaps.

Something that happens. / A spontaneous or improvised event, especially one that involves audience participation.

present participle of happen

(slang, of a place) Busy, lively; vibrant, dynamic; fashionable. / (slang, of a person or product) Trendy, up-to-the-minute.

simple past tense and past participle of happen