Despite the discovery of a Higgs-like particle in 2012, there are still many unanswered questions. Studying events with the same-sign dilepton and multilepton (SSML) may help to gain insight into those questions. SSML events have relatively low rates in the Standard Model (SM) and are expected in many extensions to the SM. In this presentation, I will give an overview of physics and challenges related to the analyses of SSML events, focusing on the analyses I worked on, namely, studies of ttH and ttW production and evidence for four-top production with the ATLAS detector.