Idiom: on (one's) toes

Meaning:

• be alert, energetic or ready; stay alert and watchful [see American-Slangs.com]
• ready to act; alert [see The Free Dictionary]

Sample usage from an article from DownloadSquad.com:

Todd said...
Missing from the list... are the Android Developers Challenge winners announced Monday... I would like to take this moment to re-state my tinfoil hat conspiracy theory that DLS has a "news black-out" on all things Android.

Christina Warren said...
Direct your conspiracy theories to Romeo -- he should have covered that in Tuesday's Googleholic ;-) I'm innocent I tells ya! No, good call. And I wouldn't call us Android averse, just Android ambivalent. But thanks for keeping us on our toes!