Splash out is a common expression used to describe spending money on an extravagant or luxurious item or experience. However, there are several synonyms that can be used to convey a similar meaning. These include phrases such as "spend big," "splurge," "indulge," "lavish," "spendthrift," and "go all out." These terms all suggest a willingness to invest in something costly or indulgent, but with varying degrees of emphasis on the extravagance or impulsiveness of the spending. Regardless of the term used, all have a connotation of treating oneself and embracing luxury or indulgence.