'Spamton' is (obviously) the motif of Spamton, and is split into two relatively distinct parts:
A standard theme, heard in most of his songs:
('Spamton A', as heard in Spamton)
And a battle theme, heard mainly is his fights:
('Spamton B', as heard in NOW'S YOUR CHANCE TO BE A )
Finally, Spamton also has an extraneous melody, heard in a couple of songs:
('HEY EVERY !', as heard in A Real Boy! )
('HEY EVERY !'s appearances will be covered first, because they're kept separate from Spamton's other themes)
Worth noting is that, just as Spamton's name and ultimate form (Spamton NEO) reference Mettaton, so too do his motifs:
'Spamton A' is akin to Mettaton's standard theme, 'It's Showtime!',
'Spamton B' is akin to Mettaton's battle theme, 'Metal Crusher',
and 'HEY EVERY !' is akin to Mettaton's extraneous theme, 'Oh!'.
Additionally, as BIG SHOT is the only other song to quote them, this article also covers the 'Dummy!' leitmotif, both its coda and its bridge:
('Dummy! (Bridge)', as heard in Dummy! )
('Dummy! (Coda)', as heard in Dummy! )
Finally, 'Spamton B' bears a striking resemblance to a certain Homestuck track, as covered on the page 'On the Origins of Undertale and Deltarune's Leitmotifs'.
The lyrics to BIG SHOT are quite contentious, especially considering their apparent lore relevance.
Here's the lyrics as they appear in BIG SHOT:
Here's the ripped audio from the Spamton Plush's voice box (courtesy of spellbot on Youtube):
And here's an isolation of BIG SHOT 's lyrics (courtesy of introC on Youtube):
Here's (to the best of my ability) a transcription of the lyrics (in my opinion):
Think it's coming for me, answer the phone;
I can't explain until you're all alone.
It pulls the strings and makes them ring,
Note that this line of dialogue is confirmed by the flavor text:
* It pulls the strings and makes them ring.
Which can appear during the Spamton NEO fight.
until your heart gets ripped up!
Think it's coming for me,
answer the phone;
Overlayed with:
"Think it's coming for me,"
I can't explain
Overlayed with:
"answer the phone;"
until you're all alone.
It pulls the strings
and makes them ring,
Overlayed with:
"It pulls the strings"
un-Tell you what you-BIG SHOT!
Alternatively, it's possible the line "Think it's coming for me, answer the phone" is instead:
"Fingers coming for me, answer the phone;" or
"Fingers coming from the end of the phone;"
The line "I can't explain until you're all alone." is instead:
"The hands wait until you're all alone."
And the line "un-Tell you what you-BIG SHOT!" is instead:
"It-Tell me what you're really selling!