This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

ad. In a sheepish way; meekly; self-consciously; with embarrassment.

In a sheepish manner; bashfully; with mean timidity or diffidence; sillily.

ad. in a sheepish manner

"“Thank you,” he calls sheepishly, locking the car and pocketing the keys; not surprisingly, the only response is a burst of disembodied laughter."

meekly    abashedly    self-consciously