bump and grind

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic A sexually suggestive dance involving exaggerated hip movements, especially a striptease dance.
• noun by extension A combination of movements resembling such a dance, as in road racing, whitewater kayaking, or exercising; any activity involving prolonged jarring or shaking.
• verb idiomatic To perform such a dance or such movements.