给不了我嫁衣就别脱我内衣
[jĭ bù le wŏ jià yī jiù bié tuō wŏ nèi yī]
The meaning is quite direct and mature. It's a colloquial and strong way of saying “if you can't offer me commitment (marriage), don't seduce or lead me into anything casual or intimate (pre-marital relations)”. This represents a protective stance toward oneself.