冗談半分

じょうだんはんぶん

noun

•

being somewhat (half) joking, half seriously, half in jest, in a jocular vein(yojijukugo)

冗	superfluous, uselessness
談	discuss, talk
半	half, middle, odd number, semi-, part-
分	part, minute of time, segment, share, degree, one's lot, duty, understand, know, rate, 1%, chances, shaku/100