I believe I do have a timeline of events that you might find informative.
On the beach, Alex asks Russ about a little mark on his shoulder. Russ tells him that it is a tattoo of the lower jawbone of a crocodile.
He explains that a crocodile has strong muscles for closing its jaw but only weak ones for opening it. He claims that the tattoo is to remind him that strength depends on how you measure it.
In a band meeting, one of the members of Pier Pressure suggests they do a cover of A Nightingale Sang in Berkeley Square. Russ insists that they should do “the famous bit” and gives a short rendition of Woof, Woof, Woof.
After an initial stunned silence, the rest of the band start to laugh at Russ’ insistence that this is how the song goes. Their hilarity grows as Russ sings in a high-pitched voice and explains that it is the nightingale doing dog impressions.
The lead singer resolves that they are doing the song. He dismisses the rest of the band except for Russ, to whom he says: “You and me are writing a song, Jawbone.”
Russ asks a tattoo artist to give him the smallest possible tattoo which is still recognisably an animal. They decide on a crocodile because it is thin but distinctive.
When asked, Russ admits that he is only getting the tattoo because of peer pressure from his band. In fact, he tells her, that is literally the name of the band (although they spell it ‘Pier Pressure’ because of Hastings Pier).
The tattoo artist lets him change this answer so that she is allowed to give him the tattoo, but tells him that she can stop anytime he wants.