Hello,
I know that this is a strange question but it came up during a discussion i had and i wanted to know what are the options.
Suppose you have a working Ubuntu installation (personally i have one running perfectly on an external HDD)
Is there any "trick" to disallow this installation to run on another HDD...assuming that someone picks up my USB HDD and clones it to another USB HDD.
I am thinking that probably in a script i should have a variable filled with HDD serial number and if there is a mismatch abort everything
Is this doable ?

No.