MR Grumpy is set to frown on speeding motorists after £6,000 was spent on new high-tech equipment.
But drivers who keep within the limit will see a smiling face on the new electronic displays in the Ribble Valley.
Instead of being punished for speeding, the signs will frown upon motorists who exceed the speed limit, to remind them to slow down.
Police insist the move, which was first revealed earlier this year by the Lancashire Evening Telegraph, is not a soft option.
The two speed indication devices are attached to lamp and sign posts and will be rotated around 20 hotspot areas every three days.
First priorities are the villages Mellor and Sabden where police have caught motorists travelling twice the 30mph limit.
As well as giving drivers the appropriate smiling or frowning image, the battery-powered devices store information, such as the amount of traffic, average speed and number of vehicles exceeding the limit.
Speed camera bosses can then use this data to establish exactly where they need to target with mobile speed camera sites.
Inspector Bob Ford, in charge of Ribble Valley policing, said: "These devices are not a soft option. Enforcement will continue across the Ribble Valley at identified sites but these devices will be used to warn drivers against breaking the speed limit. They are more of wake up call to drivers.
"The smiling and frowning faces are definitely becoming a talking point in towns and villages, but we have received tremendous community support in relation to this project."
Police Community Support Officer Nigel Williams, who has run mobile speed camera sites, added: "We are absolutely amazed that we have been catching some vehicles travelling through villages at speeds of 60 mph."
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