I just worked a very long gig and there were very long lines for everything including balloons. Most people took it in stride and handled things well, but there were more than a few parents who set out to teach their kids the wrong way to handle things. Cutting in line is not nice. The people who wait 20 min don't like it if you go around them. Getting snotty with the balloon lady when she won't take your kid next because you are "in a hurry" or "too tired to wait in such a long line." is not endearing. It's also not very motivating for me. Want me to consider letting you cut? Pull out a hundred dollar bill. I will CONSIDER IT. No guarantees because I don't want to deal with 40 mad customers. For 2 hundred you're pretty much guaranteed to be next. LOL
otherwise get in line and act like a grown up.