Disappearing Act

Does anyone else notice that as soon as someone says you have a great quality or trait, it disappears?:

"Hi, this is my friend, Marie, she's really funny!"

I now feel obligated to say something amusing. I feel my mind racing, trying to find something, anything to say to back up the claim. All the pressure usually results in the hilarious:

"It's cold outside, Eh?"

Someone mentions your wit, intelligence, your singing ability (Okay, I'll admit there's no singing ability) and they all disappear. I turn into a mute idiot, unable to add anything of value to the conversation. In future please ensure you set expectations nice and low, for example:

"Hi, this is my friend, Marie, she's okay (I guess)"

or

"Hi, this is my friend, Marie, and I really don't know why I'm her friend"

That would be great!

Thanking you in advance,
MS