bang one's head against a brick wall
bite on granite
plow the sands
piss in the wind
dead donkey
boondoggle
slatter
truant
faff
dick around
howl at the moon
fart-arse
death march
battel
laze
waste of energy
waste of effort
bring owls to Athens
waste of time
fritter
profligacy
pound sand
bate
crap out
fizzle
tabefy
smartle
time-waste
beat off
whiffle
burn daylight
squanderingly
piss away
diddle
fiddlefuck
fool around
profligate
prodigal
spendthrift
extravagant
prat about
save
fiddle away
exercise in futility
make unnecessary
losel
lamely
firtle
corrupt
fart
putz
haste makes waste
trifle
piddle away
piddle
uneconomical
wanton away
beat one's meat
awaste
footle away
uneconomic
wanton
burnt out
coquet
stultify
wasten
like painting the Forth Bridge
hum and haw
overslack
ineffectual
spurn
impairment
stultification
scattergood
thriftless
futility
constipation
deadening
deperish
timewasting
fruitless
garbages
procrastinatingly
give something up as a bad job
overhead
fool away
slack off
spread oneself thin
throw away
fol-de-rol
wear out
bollocks
carry coals to Newcastle
that and a nickel will buy you a cup of coffee
fanny about
futz