weak in the knees

weak in the knees
also, weak at the knees

Meaning

• to be overcome by a strong feeling, usually desire
• to be caught off guard by something that upsets you
• affected by a strong emotion while being unable to do something about it
• to be very nervous

Example Sentences

1. The man makes me weak in the knees when he kisses me.
2. That cake is so good that it makes me weak at the knees, I might eat it all in one sitting.
3. I went weak in the knees when Peter took me through the haunted house, I can't believe how realistic those zombies were!
4. Hearing that my dog had been run over, I went weak in the knees and my friend had to grab my arm to keep me from collapsing.
5. When they called me to go on stage I went weak in the knees.
6. The boy said that he could not help but ask me out, as the sight of me in my lovely dress had made him go weak in the knees.

Origin

It is unclear when the phrase originated, but it is meant to convey that the blood has left someone's system and they have been left weak. This can be because of shock or because they are overcome with desire.