Oxygen alternative

The bug bit Pat, too!!! (If I can own up to mis-identifying someone's gender, I can bust on my friend/work associate, too!)
Long story short, while making deliveries today, Pat got pulled over by Department of Transportation officials. He was cited for a couple of code violations on his truck, including a tire severely under-pressured. Seems he had run over a nail on the road earlier in the morning. He had to wait where he was until a mechanic came to replace the tire and repair the other problems.
When the repairman came with the tire, it too was a bit low on air pressure. Pat called the boss, "Bobby," to let him know. Bobby told Pat to fill it up with air. Meaning to ask if he could go to any air pump, the Freudian slip which escaped Pat's lips was, "Do I fill that up with regular air?"

As Bobby teased, "I know those nitrogen-filled tires are really big now, but..."