"Donald Trump on Thursday addressed the issue foremost on every voter’s mind—the state of his penis. The billionaire presidential candidate said at the Republican presidential debate that, with regard to his own endowment, 'There is no problem. I guarantee you'" [fusion.net]
Trump's hands may be small but it's not.
He implies that it's big what he's got.
What he means is quite plain,
It's for sure not his brain.
For the latter's not used quite a lot.