All work and no play makes Jack a dull Wall Street executive. But now a store has opened where Jack – or Jacqueline, for that matter – can liven up with some grown-up toys.

The Sharper Image – catalog business that has recently expanded into retail operations – opened at the South St. Seaport in mid-August and plans to unveil another shop at 535 Madison Ave. on Dec. 1.

The store sells quirky objects that are not exactly necessities but are great conversation pieces. Who else would have a biofeedback headset (to ease stress) for $99? A vibrating massage chair complete with stereo headrests for $1,595? A state-of-the-art Microtech flea collar for $59?

Those are some of the more practical objects at Sharper Image. The “toys” tend to be macho for example, a $30 water pistol that looks like an M-16, or an infrared target pistol. That item, which costs $179, is popular among executives, said salesman Nick Hanna. Two catalog items will not be offered in New York stores – a space-age crossbow and a century replica of a U.S. Army .45 pistol.

Another hot novelty is a “beep ‘n’ keep” key chain at $19. If you can’t find your keys in your handbag or briefcase, you clap your hands four times and the keys beep at you.

The store also carries espionage accessories – a paper shredder ($149), a cassette recorder so tiny that it can hide in a pocket ($79), and a travel trench coat ($79).

There are also some practical items at a good price a $45 terry cloth kimono, and attractive leather luggage for under $100.

It all started when Sharper Image founder Richard Thalheimer. 37, started jogging. He put a small ad for a runner’s watch in a magazine and “it had a snowball effect.” said Gavin Payne, a company spokesman.

There are now eight stores, said Payne, and sales have risen from $9 million in 1979 to $100 million in fiscal 1985.