As happens every year, Street bond players blamed last week's thin trading on the fact many buysiders were hunkering down to prepare for the annual Chartered Financial Analyst exam to be held Saturday. Joining in the fun was a spokesman for the Association for Investment Management & Research, a.k.a. the Association for Ignoring Marriage Responsibilities, who had his best material ready to roll. Have you heard the one about the test-taker who chose to use the six hour test to discuss his summer vacation plans? He hadn't put in the requisite 250 hours of studying and had to do something to fill the time, since he'd told his boss, who was in the seat behind him, that he been pulling all-nighters in order to prepare.