The go-getter
The speaker is determined to be a go-getter, someone who takes proactive action to achieve their goals

I'll be the go-getter
The speaker promises to be someone who takes initiative and is proactive in achieving their goals

Yes I am, I'll be the go-getter
The speaker reaffirms their determination to be a proactive, goal-oriented person

That's my plan, the go-getter
The speaker's plan is to be a proactive, goal-oriented person

Hi-fi boom box
A high-quality portable stereo system

Pretty girl in bobby socks
A physically attractive girl wearing bobby socks (a style of socks that reach just below the knee)

After party in a hotel room
A party that takes place in a hotel room after another event or gathering

Pretty soon there will be no moon
The party or event will last until the early morning hours when the moon is no longer visible in the sky

Stumble home in the pourin' rain
The speaker is walking home unsteadily (possibly due to intoxication) in heavy rain

Let the water ease my worried brain
The sound of the rain is comforting and has a calming effect on the speaker's anxious thoughts

Some days I just can't get along
The speaker has difficult days where they struggle to cope with their circumstances

I need a head to lean my shoulders on
The speaker needs emotional support from someone they can rely on

Palm trees, the flat broke disease
The speaker views palm trees as a symbol of poverty or financial hardship

And L.A. has got me on my knees
The city of Los Angeles has brought the speaker to their lowest point

I am the bluest of blues
The speaker is deeply sad and depressed

Every day, a different, different way to lose
The speaker faces new and varied challenges every day that make them feel like they're losing

I got a table at the Rainbow Room
The speaker has secured a reservation at a popular club, restaurant, or bar called the Rainbow Room

I told my wife I'd be home soon
The speaker promised their spouse they would return home shortly

Big ships are approaching the docks
Large ships are arriving at the harbor

Mashed potatoes in cellophane
A strange or unpleasant meal composition (possibly referring to instant mashed potatoes packaged in plastic)

I see my life goin' down the drain
The speaker feels like their life is falling apart

Hold me baby and don't let go
The speaker seeks comfort and support from their partner

Pretty girls help to soften the blow, yeah
Attractive women can make a difficult situation feel more bearable or enjoyable

The go-getter, the go-getter
Reiteration of the speaker's determination to be a go-getter

That's my plan, that's who I am
The speaker's identity is tied to their proactive, goal-oriented nature