There Are Many Angry Nigerians

There are a lot of angry Nigerians. 

However, threatening behaviour is a crime in the UK under public order and criminal law. These Nigerians are present in the UK and are therefore subject to UK law. The law is not interested in whether you were rightly angry or not. "Rig and you will die" is a clear threat. 

Legal definition of a threat in general criminal law:

Actus Reus (The Act): Making a statement or communication to another person threatening death or serious harm.

Mens Rea (The Intent): Intending that the recipient fears the threat will be carried out (or being reckless as to whether they fear it).

Conditional vs. Direct Threats: A statement like "if you rig, you will die" is conditional. In many legal systems, a conditional threat can still be a criminal offence if it places a specific individual in reasonable fear of unlawful violence.

In Nigeria the phrase has recently circulated prominently in political discourse—ahead of the upcoming presidential elections—referencing warnings against electoral malpractice (election rigging). 

The Independent National Electoral Commission (INEC) has condemned the slogan, stating through officials like Mohammed Kudu Haruna that it is dangerous, inflammatory, and capable of inciting "jungle justice" or vigilante violence against poll workers, ad-hoc staff, and political opponents. Under Nigerian constitutional law (such as Section 33 regarding the right to life), extrajudicial killing or summary execution for a crime like electoral malpractice is illegal; offenders must be handled through due process and the courts.

Some commentators and figures have argued that the statement is a warning about the natural or moral consequences of corruption, or a reminder that breaking the law carries grave risks, rather than a direct criminal threat issued by one individual to murder a specific person. Human rights lawyers have also debated whether it constitutes an explicit incitement to violence or a political slogan targeted at malpractice. 

My own opinion: When used broadly as political rhetoric or a generalised warning against a criminal/fraudulent act rather than a targeted interpersonal menace, it often falls into a grey area of inflammatory speech, public safety concern, or incitement rather than a direct prosecution for a personal threat to kill.

Video courtesy Sahara TV (Nigerians Confront INEC Chairman at Chatham House in London over Voters Register)