Unusual Phrases?

I've stumbled across some unusual words in anime song lyrics that are stumping me.

Here are a couple short verses:

NO-TEN P-KAN　空は晴れて
IPPAI OPPAI　ボク元気
トラブルと遊べ　ヤンチャ・ボーイ

NO-TEN P-KAN　頭さえて
RA-MEN ROPPAI　ハハのん気
世紀末はしゃげ　オチャメ・ガール

I'm especially baffled about
"P-KAN". It shows up in at least two different songs. I'm afraid I don't understand how to translate the things written in English letters, as well as most of the katakana (like "yancha boi"). I mean, I get some of the other stuff ("playing with trouble"), but... RA-MEN ROPPAI? What does it mean?

And from a different song, where does the word "janjaka" come from? One website said it meant "bring it on", but I wasn't sure if that was right.

Meanings and explanations would help me out a lot. :) Thank you.

I'm a Japanese. But I can't understand it too.
But I guess ''ヤンチャ・ボーイ'' means naughty boy, and ''RA-MEN ROPPAI'' means ''ラーメン６杯(six bowls of ramen)''.
And maybe ''janjaka'' is a onomatopoeia.

iirc,

ヤンチャ・ボーイ
i've never seen it in katakana, only hirigana but I a guessing it still means "mischievous boy "which goes with
オチャメ・ガール
mischievous girl

The lyrics you've got are hopelessly full of word plays :) The following is my best guess/interpretation...

1st line:
"No-ten" (or "nouten"): another word for "head"
"P-kan" (or "piikan"): another word for "completely sunny weather")

THere is a word "noutenki" meaning "carefree," "happy-go-lucky" person. "Nouten" and "noutenki" and the word "tenki" (weather) are combined here to say "Completely carefree." Which connects to the "sora wa harete" (the sky is sunny).

2nd line:
"ippai" = a lot, or one (serving/glass/bowl of food). It combines with the "genki" later in the line "genki ippai" = full of energy.
"oppai" = tits. This is just so that it rhymes with "ippai."

3rd line:
Play with trouble, mischievous boy

4th line: the same as the first

5th line:
"raamen roppai" = six bowls of ramen noodles. "roppai" rhymes with "oppai" in the 2nd line.
"haha" = laughter "nonki" = another word for happy-go-lucky, relaxed, carefree

6th line:
Have end-of-the-centry fun (or enjoy decadantly), mischievous girl.

"janjaka" is an onomatopoeic word expressing some kind of musical accompaniment or voices to cheer someone one, encourage someone. So "bring it on" may be close, depending on the context.

Wow, thank you very much, everyone. :) (Especially you, AK.)

This really helps me out. Looks like I have a ways to go before I understand word play like this.