What does this mean?
 

Telebi ga suki. Okashi ga suki. Manatsu mo suki. Mafuyu wa suki. Neruko wa sodatsu. NyokiNyoki nobiru. Umami mo wakaru. Ikasu ne. Boku wa tensai da. Boku wa hentai da.

I know what boku wa tensia da and boku wa hentai da means.

Wow, something I can actually answer!!

Terebi ga suki. = I like Television.

Okashi ga suki. = I like candy.

Manatsu mo suki. = I also like midsummer (I think that's what Manatsu means).

Mafuyu wa suki. = Erm...I like mid winter...I think.

Neruko wa sodatsu. = Um...not too sure about this. I don't understand what "Neruko" means. I know what "ko" means. I know what "neru" means (as a verb), but not together. Do you have any of the Japanese text. It might help to see how it's written.

NyokiNyoki nobiru. = NyokiNyoki to grow? NyokiNyoki grows?

Umami mo wakaru. = Whatever Umami means, I guess it would mean, "Umami" understands too.

Ikasu ne.= I can't figure out what "ikasu" would mean here.

Boku wa tensai da. = In plain form, it means, "I am a genius". That's the only definition I know of for tensai.

Boku wa hentai da. = In plain form, it means, "I am a pervert."

Most of those sentences, especially the first few seem very incomplete.

Well its the lyrics to this peelander z song called happee pee.

umami mo wakaru might be irony because all i can think of he is saying he also understands good taste (not likely by the band name) :P although i don't think umami translates as good taste in this way but couldn't think of anything else.
also ikasu might be like かっこいい。

i think theyre trying to say they grow really fast lol

Okashi is snacks, not necessarily candy.　Cookies, potato chips, etc all count as okashi.

Neruko refers who children who sleep well. "Sleeping children grow" It`s a REALLY common Japanese saying.

I`d say the best way to translate this would be "They grow like weeds."

I understand good taste.

Cool, aren`t I?

They`re not incomplete. They`re just short sentences.

でたらめ言うなよなぁ・・・　「うまみ」は名詞だよ。 juicy と　sweet　は形容詞だぜ。話にならんよ、マジで・・・� ��質問に答えるよりも、質問する側にまわった方が君の� ��めだよ。他にも似たような奴いるけどね。　

the meaning is actually:
旨味; 旨み; うま味 【うまみ】 (n) (1) good flavor (flavour); good taste; deliciousness; (2) umami (fifth category of taste, corresponding to the flavour of glutamates); (3) skill; (4) profit