The geeks ride around town on their bikes, trying out the garage door opener to confirm Neil's suspicions about his father.
A door opens when Neil clicks the opener at it, but it turns out someone is pulling in the driveway at that moment.
A relieved Neil says "I almost had a heart attack." Bill responds by saying "I'm coming Elizabeth; it's the big one!"
Bill's joking response is a reference to the 70's sitcom "Sanford and Son". Whenever Fred Sanford, played by Redd Foxx, would get really upset, he would exaggerate and claim he was having a heart attack, allowing him to join his late wife Elizabeth.