How small is the Source Theatre? So small that on this particular Saturday night, the actors waiting backstage for their next entrance can't afford to have full bladders -- the audience would hear the toilet flush and the shrieking water pipes that follow it. So small that modesty among cast members is pointless. So small that well before the six actors in Middle Age Spread take their bows, the smoke-filled dressing room they share resembles a nightclub for elves.

Onstage, they joke, bicker and bed-swap their way through the evening as three suburban couples suffering from marital malaise. The main difference between onstage and backstage is that backstage there is no room for bed-swapping. Dick Harrington, who plays a cynical, philandering professor, bursts into the dressing room after his first big scene exceedingly pleased with himself; he heard someone in the audience call him "a real s---" -- a real coup!

"My ex-wife," he shispers loudly to Joan Kelley, his onstage wife, "says you don't know what you're missing."

"I have an idea," she whispers back.

"You can't possibly."

Their dialogue is cut short by the necessity of stripping Richard deLaubenfels out of his suit and shoving him into jogging togs for the next scene.

Much like the annoyingly punctilious accountant he plays, Stephen Haines fusses continually backstage. "Tonight," Harrington warns him, "I don't want to hear about what a dreadful actor you are."

"I never say I'm dreadful," whispers Haines, wounded. "What I said is, "I did terribly out there.""

"Oh, Stephen," Beverly Bowman sighs fondly, "you're such a nerd."

After the show, everyone but Haines eats pizza at Trio's. "He hates cheese," explains Diane Couves, his state wife, "because of his childhood in France."

It pays to be tolerant. After all, they're a family -- for at least a few more weeks.