Malcolm in the Middle (2000)

S5E11 Ida's Boyfriend

Malcolm decides to get a tongue piercing but has to keep it under wraps for a month. Meanwhile, Lois' mother, Ida, arrives with news of her engagement to a wealthy Chinese man she met on a cruise. Malcolm’s situation worsens when his tongue ring becomes infected, preventing him from properly pronouncing "S's." He soon uncovers that Ida has been secretly drugging her fiancé with opiates and mood enhancers. When Lois and Hal confront her, Ida uses free food to drug them instead. Fortunately, the fiancé skips a drug treatment and realizes Ida’s true nature, leaving her at the altar. Malcolm faces consequences for his piercing. Over at the ranch, Otto’s attempt to hire a murder mystery acting troupe takes a disastrous turn.