a hollow argument Protestors at the AIDS conference in Barcelona booed HHS secretary Tommy Thompson ("Bush's Thompson") off the stage, arguing that the US doesn't give enough money to the UN Global Fund to Fight AIDS:

Protesters said Thompson continues to "make hollow arguments" that the United States is the largest contributor to the Global Fund, said Kim Nichols, an activist. [I realize that sentence doesn't parse. Blame CNN.] Protesters say Norway contributes 25 times as much per citizen, Sweden seven times and Rwanda 10 times as much (as a percentage of gross domestic product) as the United States does.

You see, it's a "hollow argument" to assert that the US is the largest contributor (which it is¹), since it's not the largest per capita contributor or the largest contributor as a fraction of GDP. The charming protestors also held signs accusing Bush and Thompson of "murder" on account of the small-ish contribution. 1. Sez here that the US has kicked in a cool $500M, while the next largest contributions (Japan, Italy, UK) are $200M each.