The aim of the present study was to explore neuronal oscillatory activity during a task of irony understanding. In this task, we manipulated implicit information about the speaker such as occupation stereotypes (i.e., sarcastic versus non-sarcastic). These stereotypes are social knowledge that influence the extent to which the speaker's ironic intent is understood. Time-frequency analyses revealed an early effect of speaker occupation stereotypes, as evidenced by greater synchronization in the upper gamma band (in the 150-250 ms time window) when the speaker had a sarcastic occupation, by a greater desynchronization for ironic context compared to literal context in the alpha1 band and by a greater synchronization in the theta band when the speaker had a non-sarcastic occupation. When the speaker occupation did not constrain the ironic interpretation, the interpretation of the sentence as ironic was revealed as resource-demanding and requiring pragmatic reanalysis, as shown mainly by the synchronization in the theta band and the desynchronization in the alpha1 band (in the 500-800 ms time window). These results support predictions of the constraint satisfaction model suggesting that during irony understanding, extra-linguistic information such as information on the speaker is used as soon as it is available, in the early stage of processing.