Knock me over with a feather
My roommate and I, Samantha was sitting and eating dinner one night. She was trying to have a conversation with me but I could not seem to concentrate. I kept yawning. Next I began to complain about how tired I was. My roommate responded with knock me over with a feather. I had never heard this expression before. But is makes complete sense.
After yawning repeatedly, and then proclaiming that in fact I was extremely tired, Samantha responded with a very sarcastic statement. In truth she could never be knocked over with a feather because she is way to heavy for a feather to push. This statement is very obvious, just as my statement, of being tired, was.