Thomas the tank?

[Wolfgang]

I understand this is cockney rhyming slang, but what does it mean?

[rekstout]

Enjoying the please of one's own company - in the onanistic sense

[akkers]

Its not true cockney but modern slang in which you use a word that sounds similar to the one you want to use. For a tommie tank you can also use Barclays (bank) Sherman (tank). Recently to enjoy a couple of Britneys would mean enjoying a few pints of beer (Britney Spears)

[paulz]

at my school in Deptford [too long ago to count] it was known as having a Jodrell [Jodrell bank] those who did it were known as Merchant [bankers]