Saucy, cheeky, rude postcards. Traditional British seaside postcards.
Before package holidays to Spain were invented and when British workers used to get one week's holiday a year, or maybe a 'works outing', they and their families would head for the nearest seaside resort, paddle in the sea, eat ice cream, shellfish, fish and chips, play games and generally have as much fun as they could cram in to a few short days. To prove what a good time they were having they would scandalise friends and family by sending saucy postcards, usually with fairly blatant double entendres...
Originals of these postcards are now quite valuable and much sought after by collectors.
One of the biggest producers was Bamforth Postcards.
Their website http://www.bamforthpostcards.co.uk will show you some samples, but if you go to Google Images and search for 'Bamforth Postcards' you'll get a better selection. How rude!