(plaintiffs brought personal injury lawsuit against farmer after plaintiffs were in motorcycle accident caused by slick substance on highway; firefighters called to field-fire at accident scene next day and believed farmer used fuel as accelerant, which was slick substance plaintiffs encountered; jury returned verdict in defendant’s favor; plaintiffs appeal alleging prejudicial error in defendant’s closing arguments when counsel stated the “prospect of financial ruin” had affected defendant for two years; after statement, plaintiffs requested permission to admit evidence of defendant’s insurance, but judge gave admonishment to jury instead; appellate court agreed argument was improper, but held not so prejudicial that admonishment could not cure it; additional evidence presented that other causes for slick substance were plausible; one judge dissented because he believed statement was too inflammatory for admonition to cure).