putt-putt also put-put 
(pŭtpŭt′) Informal
(pŭtpŭt′) Informal n.
1. A repeated or intermittent sound like that made by a small gasoline engine.
2. A small gasoline engine.
3. A vehicle, such as a boat, that is operated by a small gasoline engine.
intr.v. putt-put·ted, putt-put·ting, putt-putts or put-put·ted or put-put·ting or put-puts
1. To make a sound like that of a small gasoline engine.
2. To move while making such a sound.
[Imitative of a running engine.]