Was that woman me, standing there in those ugly-looking underpants, but with a smart sports bra, with everybody laughing around her?

underpants 是名词，由 under（在...下面）和 pants（裤子）组成，指"内裤、衬裤"，通常指男性或女性的贴身内衣裤。这里用 ugly-looking 修饰，强调内裤的外观难看。