通宵

通宵	tōng xiāo	all night / throughout the night
通	tōng	to go through / to know well / (suffix) expert / to connect / to communicate / open / to clear / classifier for letters, telegrams, phone calls etc
通	tòng	classifier for an activity, taken in its entirety (tirade of abuse, stint of music playing, bout of drinking etc)
宵	xiāo	night