This one has been going around for a few years so I recognized it right away.
Snopes - Congressional PensionsOrigins: This piece has been circulating on the Internet since April 2000. So much of it is outdated, inaccurate, or misleading, it's difficult to know where to begin.
* It is not true that Congressmen do not pay into the Social Security fund. Since 1984 they have paid into the fund just as most everyone else does. (A few odd exceptions to the Social Security program still exist, both inside and outside of government, but not for members of Congress.)
* It was true prior to 1984 that Congressmen did not pay into the Social Security fund because they participated in a separate program for civil servants (the Civil Service Retirement System, or CSRS), but that program was closed to government employees hired after 1983... <snip>
<snip>It is not true that Congressmen "paid nothing in on any kind of retirement," and that their pension money "comes right out of the General Fund." Whether members of Congress participate in the older Civil Service Retirement System or the newer Federal Employees' Retirement System (FERS), their pensions are funded through a combination of general tax provisions and contributions from the participants. Right now, members of Congress in the FERS plan must pay 1.3% of their salary to FERS and 6.2% in Social Security taxes.
MORE at link above