I know, I know, I said I wouldn't do homophones with The Lazy American T very often. Well, jeez, when's the last time I posted ANYTHING here, huh? I'd say this qualifies as "not very often." ;)
Actually I saw someone make this mistake in print just the other day, and I couldn't get it out of my head, so here we are. Enjoy.
With a D – as a noun, it's a barrier to be overcome – as a verb, it's to leap over that barrier.
With a T – to move at great speed.