McFly joined Newsround for a special trip to Africa for Comic Relief.
You can find out all about their trip by watching a special programme, called McFly's Big Red Noseround, at 10am on Saturday, 10 March, on CBBC Two.
Here's a peek at what they got up to.
Two years ago, McFly sang the official song for Comic Relief, All About You, and visited Uganda to find out what help was needed there.
This year, the boys joined Newsround on a second trip to Uganda in Africa to see what sort of projects Red Nose Day was helping.
They went back to Kamwokya, in capital Kampala, and found out how the money you raise is being spent.
Danny told us what it was like the first time they visited.
"I'd never been to anywhere like this before. You see footage on the TV, but it's never the same.
"The smells you smell and the people you meet, everything about it. You never really know what it's like until you're here."
Kids play near open sewers
Tom agreed with him about the bad conditions, especially the smell.
He said "There's meat and fish that have been left in the sun, and an open sewer nearby."
But your cash is pushing things in the right direction, and the boys noticed one big change.
"There's a massive school now," Dougie told us.
"It's got seven classrooms, instead of them having to use the church."
Hope for change
Tom and Harry meet local kids
And, as Tom pointed out, getting an education is the only way the children are going to get out of poverty.
"They can learn about diseases, and how to avoid them, be able to get a job and raise a family in a nice house. Without your money, they can't do that."
But even though Kamwokya is improving, there is a lot of work to do there and in many other parts of Uganda.
The band met lots of kids on their trip, and became friends with one boy called Rogers.
Rogers lives in a tiny house
Dougie was concerned about how he lived: "He's living in what is basically a tiny living room, with one lamp, a fridge that doesn't work, about three bunk beds and his cousin sleeps on the floor."
Comic Relief still needs money to help places like Kamwokya's local clinic beat disease, get clean water to people, and give even more kids an education.
Harry summed it up: "If everyone in Britain gave two pounds, that would raise £120 million, which would solve a lot of problems."
You can watch McFly's Big Red Noseround on CBBC Two on Saturday at 10am.