Meaning:
“母胎” means “since in the womb of one’s mother,” and “solo” is an English word that means “on one’s own, alone or unaccompanied.” This term, translated from the Korean language, refers to those who have been single their entire life so far. First used by show biz insiders in South Korea, this phrase caught on among Korean fans and then spread to China via the Internet. Chinese netizens often use it to mock themselves.
Example:
A: 听说公司新招的秘书是你介绍来的，她有男朋友吗？
Tīngshuō gōngsī xīn zhāo de mìshū shì nǐ jièshào lái de，tā yǒu nánpéngyou ma？
They say the new secretary we recruited was recommended by you. Does she have a boyfriend?
B: 不清楚，我帮你打听打听。
Bù qīngchǔ，wǒ bāng nǐ dǎtīng dǎtīng。
No idea. But I can ask around for you.
A: 我母胎solo，她斯文漂亮。如果她是单身，我想追求她。
Wǒ mǔtāi solo，tā sīwén piàoliàng。Rúguǒ tā shì dānshēn，wǒ xiǎng zhuīqiú tā。
I’ve been single all my life, and she’s cute. If she’s single, I want to be her boyfriend.