Third-person singular simple present indicative form of sell off

An attempt to sell goods or services by first supplying them unsolicited and then demanding payment.

The sales practice of talking to a customer about their needs and then proposing a (possibly bespoke) solution that meets them.

The marketing practice of having the host of a children's television segment endorse products or services.

Third-person singular simple present indicative form of sell up

(historical) To offer for sale by auction as long as a small piece of candle burns; the winning bid is the last one made before the flame goes out.

(idiomatic, originally Ireland) To betray one's comrades or countrymen; to betray a cause.

present participle of sell up

(sports) To succeed in deceiving an opposing player with a feigned action.

present participle of cross-sell