This is when your date/girlfriend refuses to give a traditional blow job at the end of the night. Instead, she will only put the tip of your penis in her mouth, and remain motionless, while you masturbate. It's a common end to a mediocre date night, where she likes you enough to help you get off. However, she will only put forth minimal effort. Universally seen as a failed attempt to get a blow job.
Guy 1. "How was your date last night with Lisa? Did she blow you?"
Guy 2. "I thought it went great, but at the end of the night I only ended up getting a McGuckin..."
Guy 1. "Bummer man."