Israelis are big on hospitality. I think it's a Jewish-mother thing.
So that when you go to visit a relative, a friend, an acquaintance... you're likely to get served lots of snacks and a hearty meal, and be asked to take more - אַל תִּתְבַיֵּש (ahl teet-bah-YESH), they would say to a male; אַל תִּתְבַּיְּשִׁי (ahl teet-bah-ee-SHEE), they'd say to a female. Don't be shy!
To be shy or to be embarrassed is לְהִתבייש (le-heet-bah-YESH).