In uk.d-i-y, Grunff wrote:

Surely you could've come up with something more injurious than custard
powder ;-)

The initial impulse was to use a condom filled with purple-dyed flour,
but on mature (yeah right) reflection that seemed an unnecessary echo
of the parliamentary stunt; and explaining to all the 7-11 year-olds
exactly why that big ballon had the funny little end-bit on it might've
been a Step Too Far ;-)

Stefek