Large pre-trained language models (PTLMs) have been shown to carry biases towards different social groups which leads to the reproduction of stereotypical and toxic content by major NLP systems. In this paper, we propose a method to use simple classifiers to probe English, French, and Arabic PTLMs to quantify the potentially harmful content they convey with respect to a set of templates and social group names. We use PTLMs to predict masked tokens using basic commonsense knowledge patterns and lists of social groups in order to verify, given a large set of causeeffect relations, how likely PTLMs enable offensive language about specific communities. Then, we shed the light on how such negative content can be triggered within unrelated and benign contexts. We address these problems by showing evidence based on a large scale study, and explain how to take advantage of our methodology to assess and mitigate the toxicity transmitted by PTLMs.