Maybe there just isn't a mattress big enough to stuff that kind of cash. But that's where thousands of UBS's millionaire clients are likely wishing they'd kept their savings, rather than in the illegal offshore accounts now under investigation by the SEC for tax fraud.

Last week, the Swiss banking giant agreed to pay $780 million in fines and turn over the names of 250 U.S. clients. Investigators are now seeking the names of 50,000 more.

So how did UBS convince so many wealthy Americans to risk tax evasion charges? Turns out greed alone wasn't enough. Court documents made public last week show dozens of UBS "advisers" made over 3,500 trips a year to the U.S. from 2002 on to promote the scheme. Mixing business and pleasure, the trips lasted several weeks at a time and included the usual wining and dining with prospects at swank restaurants, hotels and clubs.

Potential clients were also wooed with special access to UBS-sponsored parties and events across the country, from high-end art shows, classical music concerts, professional tennis and golf tournaments and yacht races, federal investigators say. And while corporate logos these days are splashed across anything from lemon stands to commercial spacecraft, Swiss-based UBS prides itself on being a main partner in a number of premiere sports and cultural in the States.

So whether you're into music, art or sports, chances are you've bumped into a few of these million-dollar tax cheats at these and other UBS-sponsored events over the years:

Art Basel Miami Beach
One giant wine and cheeser, Art Basel Miami Beach attracts more than 200 galleries and 2,000 artists from around the globe every year. UBS has been a key sponsor since 2002, about the time it's U.S. tax shelter scheme went into full gear. Talk about the art of the deal.

The Players Championship
A partnership with this PGA tournament in Ponte Vedra Beach, FL, allows UBS to offer its VIP guests a hospitality suite with views of the 17th green. Like it's own offshore accounts, UBS describes the course as an "oasis-in-hiding." As golfers say, always keep your eye on the green.

The Ravinia Festival
Sometimes financial instruments can make beautiful music. Set in Chicago from June - September, this classical music fest includes over 120 shows by the likes of Yo-Yo Ma, Joshua Bell and other superstars. A partner since 2002, UBS is also an exclusive sponsor of the Boston Symphony Orchestra, the Los Angeles Philharmonic and the Philadelphia Orchestra, among others.

America's Cup
USB was the first main sponsor of Team Alinghi, the winning yacht at the 32nd America's Cup in 2007. The bank says the partnership has "proven to be a parallel to how UBS approaches relationships with its clients." The most recent missive? Abandon ship!

Deborah Barrow is the Editor-in-Chief of wowOwow.