"Pulling a bolas" is often performed by not answering your phone and, after two rings, sending the call to voicemail. It is also often accomplished by proffering obvious lies as to why the person cannot participate in the social activity (e.g., "I need to clean my room").
The reasons for "Pulling a Bolas" can differ from person to person, but often include the following: XBox, self pleasuring activities, and the need for excessive "alone" time.
2.) "He just pulled a bolas on me. I called to see if he was still coming out tonight. Two rings and straight to voicemail."