AS THE first negative ads of this year's gubernatorial race hit the airwaves, voters might want to remember a quip from the eloquent Adlai Stevenson, who twice won the Democratic presidential nomination and twice lost to Dwight Eisenhower:

"A lie is an abomination unto the Lord and a very present help in trouble."

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TELEVISION talk show host Phil Donahue's campaign to broadcast an execution on his program has not gone unnoticed by David Letterman's writers.

A sampling of the Donahue-execution jokes heard recently on the Letterman show follows:

* "To give you an idea of how oppressively hot and humid it was in New York City yesterday, guys were showing up at the 'Donahue' show asking to be executed."

* "Phil Donahue has gone to the Supreme Court to ask if he can broadcast an execution on TV. If he can't broadcast an execution, he'll do the next best thing and show a Cubs game."

* "A worker installing a cable on an electrical transformer in Arlington, Texas, was zapped with over 14,000 volts of electricity on Tuesday. He said that all he remembers is 'one big flash of light.' Today, the guy got a call from Phil Donahue, who asked, 'Would you mind doing that again on my show?'"

* And from a recent Letterman Top Ten list of signs that Ben (of Ben and Jerry's Ice Cream) has "gone nuts": Sign No. 2 -- "Asked to be executed on 'Donahue.' "