"随便吃喝"英文表达为 "eat and drink casually" 或 "eat and drink without concern for expense"。
这个说法源于中文的习惯用语，表示不在意钱财的吃喝行为。
例句：
He's always eating and drinking casually, never worrying about the cost. 他总是随便吃喝，从不担心花钱。
They went out to eat and drink casually, not worrying about the expense. 他们出去随便吃喝，不在意花费。