This election season, I've discovered that it's not cool to make fun of people for their gender, race, religion or weight. Actually, I'm just guessing on the weight thing, because it's not like we're going to let a fat person run for president. Which, I'm trying to point out here, is totally a bad thing. But for some reason, it's still OK to make fun of old people. And because most comedians - at least those who don't have a piano and a painfully long deal with PBS - won't tackle subjects such as healthcare and foreign policy, 50 percent of the political humor from now to November will be about how John McCain is too old. David Letterman already has a regular monologue bit about it - which McCain showed up to counter Tuesday night - that goes like this: "He looks like an old guy in a coffee shop who's still complaining about the designated hitter. ... He looks like the guy at the supermarket who is confused by the automatic doors." Bill Maher has said that McCain's pickup line is "Did you know that 150 is the new 130?" and last week suggested a video game called John McCain's Virtual Fireplace. The Web site Johnmccainisyourjalopy.com delivers comments at random, such as "John McCain heads to the airport four hours early" and "John McCain would remember where he put it if you would just shut up." Even the Democratic National Committee put out "Top 10 Reasons to Vote for John McCain," which included "Early-bird specials at the White House cafeteria." The Democrats have been to the White House so rarely in the last eight years, they think it has a cafeteria. MAYBE IT'S acceptable to make fun of old people because they can't hurt you. Or because it's rude to mock the dead, so we want to get in our shots while we still can. Or maybe because as long as our cruel jokes are delivered at a normal speaking volume, they'll never know. I called my 87-year-old grandmother in Fort Lauderdale, Fla., to find out what she thought. Before we could get to why Americans poke fun at the elderly, we had to have a pre-conversation I didn't see coming: "He's not old," said Mama Ann about McCain. "No, I don't consider him an old man." She explained that lots of older people have been president, like "that man, what's-his-name, the one after Kennedy was shot." Once we established that McCain would, at 72, be the oldest man to be inaugurated as president, we could move on to her feelings about old-person jokes. "It's insulting," she said. "We don't sit on our cannies anymore. We get out more and do different causes that makes our mind go ticking. We have so much more to do now. We have the DVD. We try to help other people. We don't ask for much. And they're not giving us much." Apparently when the elderly do ask for much, they do it very passive-aggressively. SO I was feeling pretty bad about how we mock our senior citizens, until I ran some of Letterman's offensive jokes by Mama Ann. When I got to "He looks like the guy at the hardware store who makes the keys," she started cracking up. "He is not very stately looking," she said. "He needs a new tailor to get sharp looking." And when I read her the jalopy Web site's line "John McCain has an extra gallon of windshield washer fluid if you need it," the lifelong Democrat was very impressed with the man: "You should always have reserves. I always have an extra gallon of water in the house or two. And tuna. And I always have an extra gallon of orange juice in the freezer. Just in case I run out." When I recited a joke about McCain avoiding too much pepper, she thought that also was wise: "Spicy food really does not sit right with older people. The tummies can't take the spice anymore. Except for the Orientals." Before any Asians get offended, understand this is an enormous improvement over her longtime use of another, significantly more offensive epithet. Also, Asian people, remember how often you make fun of old people. Unless your culture really does revere its elders. In which case, go ahead and send an angry e-mail to my grandmother. She'll get right back to you. Before we got off the phone, Mama Ann told me that I shouldn't worry too much: "The older people don't care. They're so happy they got that age, they don't care." That's why jokes about old people are OK. They're not belittling others for their differences the way that racist and sexist jokes do; they're actually about the human condition. We all hope to get old, and we're all scared about losing our eyesight, our memory, our ability to tip well. They're jokes about our own mortality. Luckily, if there's one guy tough enough to face his mortality, it's John McCain. The writer is a columnist for the Los Angeles Times.