When frustration got the better of him, Jimmy Durante used to raise his hands to heaven, slap them to his sides and exclaim, "I'm surrounded by assassins!"

Today we're surrounded by con men eager to relieve us of whatever isn't nailed down.

Let me give you a few examples supplied by readers recently.

One of the reasons the mails are so heavy these days is the proliferation of letters from people who say they want to help us get rich overnight. A favorite attention-getter is the headline that first greets the recipient's eye as he opens the letter: "How would you like to earn $500,000 in the next 90 days?"

What follows is a glowing report about hundreds of satisfied customers who have raked in fabulous sums after investing only a few dollars in this sure-fire scheme.

The argument is advanced that if other people just like you could make so much money, you will be able to do it, too. Just send $2 or $5 or some similarly modest amount for complete details.

Those who send in the required fee get back a letter that advises them to buy a mailing list and send out the same kind of letter to every name on it, and then to reinvest their profits in bigger mailing lists until they have as much money as they want.

Those who don't want to spend their time addressing envelopes can follow the example of our old friend The Panhandler. Ralph Rouse reports that The Panhandler is alive and well, and apparently still making a fine living with his simple act. Ralph says his encounter with The Panhandler took place while he was walking in the vicinity of Connecticut Avenue and Quebec Street. Ralph writes:

"A nicely dressed white man asked me, 'Excuse me, do you live around here?' I said I did.

"He said, 'Could you lend me 90 cents? Some black kids siphoned all the gas out of my car.' I replied, 'Gee, I have always wanted to meet you. I have read so much about you in Bill Gold's column.' He gave me a look of disdain and quickly walked away."

The latest scam reported to me is more vicious. Natalie Brott hired two lads of about 19 to mow her lawn and trim some bushes. While they were working, a phone call came in for one of the young men. His mother was calling to let him know that "they came to take your car away to be fixed."

The young man was puzzled. He hadn't asked anybody to do anything to his car. He had planned to fix it himself. Who had taken his car?

Now it was the mother's turn to be puzzled. "You said your car needed fixing," she explained, "and a few minutes ago some men in a tow truck came by and said they were hauling it in to be fixed. I thought you had arranged it."

After he hung up, the young man told Natalie, "This kind of thing happens frequently. It's a new way to steal cars. Some of them are just stripped for parts and abandoned."

Also new to me is the scam in which several men to turn up at an unoccupied house and begin doing yard work. The activity engaged in by the men seems legitimate, so neighbors accept their presence without suspicion.

But later, while some of the men are still working in the yard, others break into the house and loot it.

If your neighbors are at work when strange men arrive to tidy up their yard, phone your neighbors at work and ask whether they contracted for yard work to be done. If your neighbors are out of town or for some other reason not reachable by phone, write down the license number of the vehicle used by the "yard workers" plus a careful description of it.

If you can, count how many men arrive. Later count how many remain visible to you in the yard. If your second count is less than the first one, dial 911 and let the police check them out.

The police will tell you that one of the best defenses against residential burglary is an alert and concerned neighbor. POOR AMTRAK

It now appears that the Reagan administration is destined to stop more passenger trains than Jesse James did. THESE MODERN TIMES

Robert Fleming of the Chicago Tribune comments:

"Nothing makes you feel that your home is your castle more than getting an estimate to have it painted."