Calculate Swatch Internet Time
PHP, 12 bytes

&lt;?=@date(B);


But it can only be so short because PHP has built-in Swatch Internet Time support. So this answer isn't much fun.



&lt;?= exits HTML mode and evaluates an expression, then echoes it.

@ silences an error.

date() outputs the current time, formatting it with a given format string.

B is an undefined constant. In PHP, if you reference a constant that doesn't exist, you get back a string containing its name, and it also produces a “notice”-level error. Here, the @ suppresses that error. B is the date() format code for Swatch Internet Time.

; terminates the expression.



If we assume PHP is being run with the default error-reporting settings, where “notices” are silenced, we could skip the @, and it would only be 11 bytes.