我要在你生命里猖狂一辈子

This user name roughly means: 'I want to be wild in your life forever'. 'Wild' here is intended in the sense of unrestrainedly doing things without much consideration of convention and public order. This sentence shows that the person would be present as one who does not live up to expectation but passionately expresses feelings and desires freely around his object of love during all the rest of the lifetime.