(1) adv - "seriously?", expressing doubt/surprise or asking for confirmation
(2) exclamation/statement issuing confirmation
(3) agreement
(1) yo girl is preggers with triplets?! for serious?!
(2) for serious, that chick wants my ass!
(3) "that teacher is dumb ass hell."
"for serious, man."
a combination of the phrases "for real" and "seriously", "for serious" can express agreement when used as an exclamation, it can also be phrased as a question.
Example 1:
person A: "Hey, I got a new cell phone today"
person B: "For serious?"
Example 2:
person A: "That girl is such a ditz"
person B: "for serious!"
A combination of the phrases "for real" and "seriously". The two are combined to form "for-serious", adapted later to "ferserious" meaning "really serious." Most commonly used in question form.
"When I first heard that Anna and Billy were going steady, I didn't think it was ferserious, so I asked outloud 'Are you ferserious?!?'"