Sandbagging

noun
1.
a bag filled with sand, used in fortification, as ballast, etc.
2.
such a bag used as a weapon.
verb (used with object), sandbagged, sandbagging.
3.
to furnish with sandbags.
4.
to hit or stun with a sandbag.
5.
Informal.

to set upon violently; attack from or as if from ambush.
to coerce or intimidate, as by threats:
The election committee was sandbagged into nominating the officers for a second term.
to thwart or cause to fail or be rejected, especially surreptitiously or without warning:
He sandbagged our proposal with his snide remarks to the boss.

6.

Poker. to deceive (one or more opponents) into remaining in the pot by refraining from betting on a strong hand, then raising the bet in a later round.
Informal. to gain an advantage over (one or more competitors) by concealing one’s abilities or other strengths early in a game or other competitive activity.
Informal. to gain an advantage by concealing or downplaying the strengths of (something):
companies that sandbag their earnings estimates and then easily beat them to make everyone happy.

verb (used without object), sandbagged, sandbagging.
7.

Poker. to sandbag one or more opponents.
Informal. to sandbag an opponent or competitor:
guys that sandbag and fall back a little in the first race to get a better starting spot in the second.

noun
1.
a sack filled with sand used for protection against gunfire, floodwater, etc, or as ballast in a balloon, ship, etc
2.
a bag filled with sand and used as a weapon
verb (transitive) -bags, -bagging, -bagged
3.
to protect or strengthen with sandbags
4.
to hit with or as if with a sandbag
5.
(finance) to obstruct (an unwelcome takeover bid) by prolonging talks in the hope that an acceptable bidder will come forward
sandbag