A Zimbabwean security guard who joked at work about President Robert Mugabe’s fondness for cookies and soft drinks is going on trial and faces up to 12 months in jail for “undermining the authority” of Mugabe. It is the latest in a spate of charges, arrests and imprisonments under a law banning anti-presidential insults. Accusations often emerge from the workplace, from conversations eavesdropped by plainclothes security agents on commuter buses and even from legal opposition political rallies.