OK, getting off topic, but I can't resist - the way the Brits mix up their units of measure is really quite amusing. In most of the world people use the metric system. In the US we use the imperial system, which is bizarre but at least we're consistent. But in the UK you have a very strange mix of measurements:
Milk, water, etc are sold in litres, but beer is sold in pints and gasoline in gallons (which are different than our gallons by the way).
Length is in metres, unless you're on the motorway in which case it's in miles and sometimes yards.
Weight is in kilos, unless you're talking about how much a person weighs, in which case it's stones.
But back to the question about "sussed" - I must admit I've not heard it, though I deal regularly with folks in the UK who use terms like "it's gone pear-shaped" and "bespoke" (I had to look that one up when I first came to work here). And I have learned that the way we pronounce the word "solder" here in the US makes my British friends smirk. ;)