Háizi máchán le bàntiān, māma cái dāyìng mǎi wánjù.
The kid pestered Mom for ages before she finally agreed to buy the toy.
Tips
usage
Colloquial; close in meaning to 纠缠 but more informal and often used for trivial pestering rather than entanglement. Compare 麻烦 "to trouble": 麻缠 implies persistence over time, whereas 麻烦 is a one-off favor.
memory
Both 麻 (numb / hemp / annoying) and 缠 (to wind, entangle) carry sticky-bothersome connotations. 麻缠 is essentially "annoyingly clingy", the perfect verb for a toddler or a salesperson who won't leave you alone.