Yes Konami codes still work
No they're NOT that generous...

that code was for Contra and it was 30 lives. They also had a modified version in Gradius that would give you all the powerups and another gradius game would troll the player by destroying them instead. . .
well, a googke search has turned up many games that have this code in them

side note : i have a theory that the code is a reference to Top Gun NES when you're trying to refuel the refueling plane drops a hose and you have to line yourself up perfectly and the game keeps saying UP UP! Down Down! LEFT! RIGHT! and then the refueling plane just gives up and leaves you there. . .

@Icedfate: You should write your theory at gamefaqs and/or other places. Its important that it becomes written down for future. You may be the first to find it out. I thought those who made games wrote it down when they made them. I have a friend that found out in late 90s how to get 100% in Doom 95. He never published it and ca 20 years later another came by and were considered the ''first''. You should write your full name. I have an code printed code book from 90s and discovered that many of them werent written down and wrote down only some of them.

well my theory was just that some konami dev started using the code as a joke, because top gun was the first konami game made for nes, and i bet even in playtesting, that frustrations with the refueling plane came up, but they left it in the game anyway and then created the up up down down code for future games as a nod to that.

I have no evidence or proof and there's no way to test this theory, but hey, it's just a theory. . .a game theo. . .nevermind

@Icedfate: Theres no way to test the theory, as you write. Maybe some developers that are at Konami now and read discussion posts at steam knows some of the old developers or maybe their the same. Maybe writing to the company website. My point is that developers should have written how they come up with various things for history to keep.

I myself have never tried the codes because I didnt knew exactly how they were. It was an older friend that told me in the 90s that he had heard from another. That there existed a code in TMNT something up, down, A,B something that would give you 99 lives.

if it's that important to you, feel free to steal my theory and post it. i'm just planting the seed.