slap onto

slap onto

To apply something to oneself or something else very hastily or haphazardly. A noun or pronoun can be used between "slap" and "onto." Don't just slap makeup onto your face like that—you need to learn how to put it on properly. I can't understand why this artist is so revered. It looks like he just slapped paint onto the canvas and left it at that.
See also: slap
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

slap something onto someone or something

 and slap something on
to place something onto someone or something by slapping. Tim slapped a sign onto Gary that said "kick me." Tim came up to Gary's back and slapped on a sign.
See also: slap
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.
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References in periodicals archive ?
Summary: Domino pieces rapidly slap onto the table in the opening salvo.
This comes on top of the so-called disloyalty charges that some banks already slap onto customers who use other cash machines.
To combat such bruising blows to skin and confidence Laboratoires Garnier have developed an emergency patch to slap onto the offending pimple.