kimberly bell photos

Government witness, Playboy Playmate, and former Barry Bond's mistress, Kimberly Bell, will take the stand in Barry's perjury trial, mainly to dish about the Big Head sluggers incredibly shrinking balls. The government is making the case that as his head got bigger, his sack was shrinking, a sure fire sign of steroid use.

The government's pre-trial filings say that Bell, who posed nude for Playboy in November 2007, will testify that beginning in 2000 she observed Bonds with "bloating, acne on the shoulders and back, hair loss and testicle shrinkage" - all documented side-effects of steroid abuse. Bell is also expected to say Bonds told her about his steroid use and suffered from steroid-fueled rages.

In addition to the shrinkage, the government is also bringing a former Giants trainer to the stand to testify how Barry's big head was out-growing his baseball cap.

Other witnesses the government plans to bring to the stand this week include IRS agents Mike Wilson and Ana Geter, former Giants trainer Stan Conte, and the team's equipment manager, Mike Murphy, who prosecutors have indicated will testify that Bonds' cap size grew while he was with the team.

How much more evidence does one need?