Don't take my experience as factual evidence or guarantee of success.
But I traveled to the US on the VWP in November of 2007 and stayed for 2 months. I was then home for 6 weeks, and traveled back in March 2008 and stayed for 88 days. I thus spent 5 months in the US over a 6.5 month time frame.
On my entry in March 2008 I went to secondary inspection. This is what happened:
CBP: What's the purpose of your visit today?
Me: Visiting friends.
CBP: Who do you know here?
Me: I have plenty of friends here, I was a student here in college.
CBP: You were a student huh? Can you come with me?
He took me into a waiting room where I waited for about 10 minutes. Another CBP officer behind a desk then told me to come up.
CBP: What do you do back home?
Me: I am a .....
CBP: Who are you staying with?
Me: A friend from college.
CBP: Your girlfriend?
Me: No, just a friend.
CBP: Ok, one moment.. (He then looked through my passport, and typed a bit on his computer, then handed me my passport back) Ok, have a nice stay.
When I exited towards baggage claim, another CBP officer came up to me and said:
CBP: Hi! Who are you visiting?
Me: My friend.
CBP: Your girlfriend?
Me: No, my friend.
CBP: Ok sir, have a good day!
So to answer your question, yes, it's a fully possible "stunt" to pull off, but expect some questions.
